Faculty Profiles - OKUMURA Akira

Characterization of Markarian 421 during its most violent year: Multiwavelength variability and correlations Open Access

Abe K., Abe S., Abhir J., Abhishek A., Acciari V.A., Aguasca-Cabot A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Asano K., Baack D., Babiäa A., Barres De Almeida U., Barrio J.A., Batkoviäa I., Bautista A., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Bronzini E., Burelli I., Campoy-Ordaz A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Cerasole D., Ceribella G., Chai Y., Cifuentes A., Colombo E., Contreras J.L., Cortina J., Covino S., DâÂ€Â™ amico G., DâÂ€Â™ ammando F., DâÂ€Â™ elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., De Menezes R., Delfino M., Delgado J., Delgado Mendez C., Di Pierro F., Di Tria R., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsaesser D., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinoviäa N., Gradetzke T., Grau R., Green D., Green J.G., Günther P., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera Llorente J., Hrupec D., Imazawa R., Ishio K., Jiménez Martínez I., Jormanainen J., Kankkunen S., Kayanoki T., Kerszberg D.

Astronomy and Astrophysics Vol. 694 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Aims. Mrk 421 was in its most active state around early 2010, which led to the highest TeV gamma-ray flux ever recorded from any active galactic nuclei (AGN).We aim to characterize the multiwavelength behavior during this exceptional year for Mrk 421, and evaluate whether it is consistent with the picture derived with data from other less exceptional years. Methods. We investigated the period from November 5, 2009, (MJD 55140) until July 3, 2010, (MJD 55380) with extensive coverage from very-high-energy (VHE; E > 100 GeV) gamma rays to radio with MAGIC, VERITAS, Fermi-LAT, RXTE, Swift, GASP-WEBT, VLBA, and a variety of additional optical and radio telescopes. We characterized the variability by deriving fractional variabilities as well as power spectral densities (PSDs). In addition, we investigated images of the jet taken with VLBA and the correlation behavior among di_erent energy bands. Results. Mrk 421 was in widely di_erent states of activity throughout the campaign, ranging from a low-emission state to its highest VHE flux ever recorded. We find the strongest variability in X-rays and VHE gamma rays, and PSDs compatible with power-law functions with indices around 1.5. We observe strong correlations between X-rays and VHE gamma rays at zero time lag with varying characteristics depending on the exact energy band. We also report a marginally significant (_3_) positive correlation between high-energy (HE; E > 100 MeV) gamma rays and the ultraviolet band. We detected marginally significant (_3_) correlations between the HE and VHE gamma rays, and between HE gamma rays and the X-ray, that disappear when the large flare in February 2010 is excluded from the correlation study, hence indicating the exceptionality of this flaring event in comparison with the rest of the campaign. The 2010 violent activity of Mrk 421 also yielded the first ejection of features in the VLBA images of the jet of Mrk 421. Yet the large uncertainties in the ejection times of these unprecedented radio features prevent us from firmly associating them to the specific flares recorded during the 2010 campaign. We also show that the collected multi-instrument data are consistent with a scenario where the emission is dominated by two regions, a compact and extended zone, which could be considered as a simplified implementation of an energy-stratified jet as suggested by recent IXPE observations.

DOI： 10.1051/0004-6361/202451624

Time-dependent modelling of short-term variability in the TeV-blazar VER J0521+211 during the major flare in 2020

MAGIC Collaboration , Abe S., Abhir J., Abhishek A., Acciari V.A., Aguasca-Cabot A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Barres De Almeida U., Barrio J.A., Batković I., Bautista A., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Bronzini E., Burelli I., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Cerasole D., Ceribella G., Chai Y., Cifuentes A., Colombo E., Contreras J.L., Cortina J., Covino S., D'Amico G., D'Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., De Menezes R., Delfino M., Delgado J., Delgado Mendez C., Di Pierro F., Di Tria R., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsaesser D., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Gradetzke T., Grau R., Green D., Green J.G., Günther P., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera Llorente J., Hrupec D., Imazawa R., Ishio K., Jiménez Martínez I., Jormanainen J., Kankkunen S., Kayanoki T., Kerszberg D.

Astronomy and Astrophysics Vol. 694 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Self-repairing graphite protective layer has been discovered as a suitable protective layer in blast furnace (BF) hearth in recent years. In the current study, actual samples of self-repairing graphite protective layer taken from a commercial BF were analyzed in detail. The results revealed that the hot face of graphite protective layer exhibits a distinct white graphite luster, with large areas of graphite adhering to the surface. Along the direction of its formation, the sample displays a striped pattern with alternating layers. The graphite is strip-shaped, it is relatively coarse and unevenly distributed. The coarse graphite runs in the same direction, unlike graphite in molten iron which has no fixed direction in a chaotic state. The formation process of selfrepairing graphite protective layer can be concluded, graphite precipitates at the interface through heterogeneous nucleation. Crystal nuclei often preferentially adhere to the surface of these impurities to form, owing to the fact that the nucleation energy of heterogeneous nucleation is lower than that of homogeneous nucleation. Titanium is discovered during the observation of microscopic morphology of graphite protective layer, graphite protective layer is more robust due to the strengthening effect of titanium. Titanium strengthening mechanism of self-repairing graphite protective layer is summarized, the strengthening mechanism can be divided into four steps. TiC particles are dispersed around graphite, which reduces the difficulty of the orientation of flake graphite growth. The presence of TiC increases the growth rate of crystals. The four steps are cyclically performed, so the self-repairing graphite protective layer can precipitate layer by layer through titanium strengthening mechanism, which serves to protect the carbon brick in BF hearth.

DOI： 10.1051/0004-6361/202451378

Cosmic-ray acceleration and escape from supernova remnant W44 as probed by Fermi-LAT and MAGIC

Abe, S; Abhir, J; Abhishek, A; Acciari, VA; Aguasca-Cabot, A; Agudo, I; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Asano, K; Babic, A; Baquero, A; de Almeida, UB; Barrio, JA; Batkovic, I; Bautista, A; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Bronzini, E; Burelli, I; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Cerasole, D; Ceribella, G; Chai, Y; Chilingarian, A; Cifuentes, A; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; de Menezes, R; Del Popolo, A; Delfino, M; Delgado, J; Mendez, CD; Di Pierro, F; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fröse, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Gliwny, P; Godinovic, N; Gozzini, SR; Gradetzke, T; Grau, R; Green, JG; Günther, P; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Herrera, J; Hrupec, D; Hütten, M; Imazawa, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kayanoki, T; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Láinez, M; Lamastra, A; Leone, F; Lindfors, E; Linhoff, L; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Lyard, E; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Martínez-Chicharro, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nakamori, T; Nanci, C; Nava, L; Neustroev, V; Nickel, L; Rosillo, MN; Nigro, C; Nikolic, L; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Peresano, M; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Silvestri, G; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Tajima, H; Takahashi, M; Takeishi, R; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Viale, I; Vigorito, CF; Vitale, V; Vovk, I; Walter, R; Will, M; Wunderlich, C; Yamamoto, T; Di Tria, R; Di Venere, L; Giordano, F; Bissaldi, E; Green, D; Morlino, G

ASTRONOMY & ASTROPHYSICS Vol. 693 2025.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. The supernova remnant (SNR) W44 and its surroundings are a prime target for studying the acceleration of cosmic rays (CRs). Several previous studies established an extended gamma-ray emission that is set apart from the radio shell of W44. This emission is thought to originate from escaped high-energy CRs that interact with a surrounding dense molecular cloud complex. Aims. We present a detailed analysis of Fermi-LAT data with an emphasis on the spatial and spectral properties of W44 and its surroundings. We also report the results of the observations performed with the MAGIC telescopes of the northwestern region of W44. Finally, we present an interpretation model to explain the gamma-ray emission of the SNR and its surroundings. Methods. We first performed a detailed spatial analysis of 12 years of Fermi-LAT data at energies above 1 GeV, in order to exploit the better angular resolution, while we set a threshold of 100 MeV for the spectral analysis. We performed a likelihood analysis of 174 hours of MAGIC data above 130 GeV using the spatial information obtained with Fermi-LAT. Results. The combined spectra of Fermi-LAT and MAGIC, extending from 100 MeV to several TeV, were used to derive constraints on the escape of CRs. Using a time-dependent model to describe the particle acceleration and escape from the SNR, we show that the maximum energy of the accelerated particles has to be '40 GeV. However, our gamma-ray data suggest that a small number of lower-energy particles also needs to escape. We propose a novel model, the broken-shock scenario, to account for this effect and explain the gamma-ray emission.

DOI： 10.1051/0004-6361/202449748

Event reconstruction using pattern spectra and convolutional neural networks for the Cherenkov Telescope Array

Wilkinson M.H.F., Peletier R.F., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E., Bernardos M.I.

Proceedings of Science Vol. 417 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the future observatory for ground-based imaging atmospheric Cherenkov telescopes. Each telescope will provide a snapshot of gamma-ray induced particle showers by capturing the induced Cherenkov emission at ground level. The simulation of such events provides camera images that can be used as training data for convolutional neural networks (CNNs) to differentiate signals from background events and to determine the energy of the initial gamma-ray events. Pattern spectra are commonly used tools for image classification and provide the distributions of the sizes and shapes of features comprising an image. The application of pattern spectra on a CNN allows the selection of relevant combinations of features within an image. In this work, we generate pattern spectra from simulated gamma-ray images to train a CNN for signal-background separation and energy reconstruction for CTA. We compare our results to a CNN trained with CTA images and find that the pattern spectra-based analysis is computationally less expensive but not competitive with the purely CTA images-based analysis. Thus, we conclude that the CNN must rely on additional features in the CTA images not captured by the pattern spectra.

CTC and CT5TEA: An advanced multi-channel digitizer and trigger ASIC for imaging atmospheric Cherenkov telescopes Open Access

B. Schwab, A. Zink, G. Varner, D. Depaoli, J. Hinton, G. Liu, A. Okumura, D. Ross, J. Schäfer, H. Schoorlemmer, H. Tajima, J. Vandenbroucke, R. White, J.J. Watson, J. Zorn, S. Funk

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Vol. 1069 2024.12

Language：English Publishing type：Research paper (scientific journal)

We have developed a new set of Application-Specific Integrated Circuits (ASICs) of the TARGET family (CTC and CT5TEA), designed for the readout of signals from photosensors in cameras of Imaging Atmospheric Cherenkov Telescopes (IACTs) for ground-based gamma-ray astronomy. We present the performance and design details. Both ASICs feature 16 channels, with CTC being a Switched-Capacitor Array (SCA) sampler at 0.5 to 1 GSa/s with a 16,384 sample deep storage buffer, including the functionality to digitize full waveforms at arbitrary times. CT5TEA is its companion trigger ASIC (though may be used on its own), which provides trigger information for the analog sum of four (and 16) adjacent channels. Since sampling and triggering takes place in two separate ASICs, the noise due to interference from the SCA is suppressed, and allows a minimal trigger threshold of ≤ 2.5 mV (0.74 photo electrons (p.e.)) with a trigger noise of ≤ 0.5 mV (0.15 p.e.). For CTC, a maximal input voltage range from −0.5 V up to 1.7 V is achieved with an effective bit range of > 11.6 bits and a baseline noise of 0.7 mV. The cross-talk improved to ≤ 1% over the whole −3 dB bandwidth of 220 MHz and even down to 0.2% for 1.5 V pulses of 10 ns width. Not only is the performance presented, but a temperature-stable calibration routine for pulse mode operation is introduced and validated. The resolution is found to be ∼ 2.5% at 33.7 mV (10 p.e.) and ≤ 0.3% at 337 mV (100 p.e.) with an integrated non-linearity of < 1.6 mV. Developed for the Small-Sized Telescope (SST) and Schwarzschild-Couder Telescope (SCT) cameras of the Cherenkov Telescope Array Observatory (CTAO), CTC and CT5TEA are deployed for both prototypes and shall be integrated into the final versions.

DOI： 10.1016/j.nima.2024.169841

Constraints on VHE gamma-ray emission of flat spectrum radio quasars with the MAGIC telescopes Open Access

Abe, S; Abhir, J; Abhishek, A; Acciari, VA; Aguasca-Cabot, A; Agudo, ; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Artero, M; Asano, K; Babic, A; Baquero, A; de Almeida, UB; Barrio, JA; Batkovic, ; Bautista, A; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Bronzini, E; Burelli, ; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Cerasole, D; Ceribella, G; Chai, Y; Cifuentes, A; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Ammando, F; D'Elia, ; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; de Menezes, R; Del Popolo, A; Delfino, M; Delgado, J; Mendez, CD; Di Pierro, F; Di Tria, R; Di Venere, L; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fröse, S; Fukami, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Gradetzke, T; Grau, R; Green, D; Green, JG; Günther, P; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Herrera, J; Hrupec, D; Hutten, M; Imazawa, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kayanoki, T; Kerszberg, D; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Láinez, M; Lamastra, A; Leone, F; Lindfors, E; Linhoff, L; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Lyard, E; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Martínez-Chicharro, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nakamori, T; Nanci, C; Neustroev, ; Nickel, L; Rosillo, MN; Nigro, C; Nikolic, L; Nilsson, K; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Peresano, M; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Silvestri, G; Sitarek, J; Sliusar, ; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Tajima, H; Takahashi, M; Takeishi, R; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Viale, ; Vigorito, CF; Vitale, V; Vovk, ; Walter, R; Will, M; Wunderlich, C; Yamamoto, T; Zywucka, N; Ramazani, VF; Buson, S; Ciprini, S

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 535 ( 2 ) page： 1484 - 1506 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Monthly Notices of the Royal Astronomical Society

Flat spectrum radio quasars (FSRQs) constitute a class of jetted active galaxies characterized by a very luminous accretion disc, prominent and rapidly moving line-emitting cloud structures (broad-line region, BLR), and a surrounding dense dust structure known as dusty torus. The intense radiation field of the accretion disc strongly determines the observational properties of FSRQs. While hundreds of such sources have been detected at GeV energies, only a handful of them exhibit emission in the very-high-energy (VHE, E ≥ 100 GeV) range. This study presents the results and interpretation derived from a cumulative observation period of 174 h dedicated to nine FSRQs conducted with the Major Atmospheric Gamma-ray Imaging Cherenkov telescopes from 2008 to 2020. Our findings indicate no statistically significant (≥5σ) signal for any of the studied sources, resulting in upper limits on the emission within the VHE energy range. In two of the sources, we derived quite stringent constraints on the gamma-ray emission in the form of upper limits. Our analysis focuses on modelling the VHE emission of these two sources in search for hints of absorption signatures within the BLR radiation field. For these particular sources, constraints on the distance between the emission region and the central black hole are derived using a phenomenological model. Subsequently, these constraints are tested using a framework based on a leptonic model.

DOI： 10.1093/mnras/stae2313

Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode

Algaba J.C., Baloković M., Chandra S., Cheong W.Y., Cui Y.Z., D'Ammando F., Falcone A.D., Ford N.M., Giroletti M., Goddi C., Gurwell M.A., Hada K., Haggard D., Jorstad S., Kaur A., Kawashima T., Kerby S., Kim J.Y., Kino M., Kravchenko E.V., Lee S.S., Lu R.S., Markoff S., Michail J., Neilsen J., Nowak M.A., Principe G., Ramakrishnan V., Ripperda B., Sasada M., Savchenko S.S., Sheridan C., Akiyama K., Alberdi A., Alef W., Anantua R., Asada K., Azulay R., Bach U., Baczko A.K., Ball D., Bandyopadhyay B., Barrett J., Bauböck M., Benson B.A., Bintley D., Lackburn L., Blundell R., Bouman K.L., Bower G.C., Boyce H., Bremer M., Brissenden R., Britzen S., Broderick A.E., Broguiere D., Bronzwaer T., Bustamante S., Carlstrom J.E., Chael A., Chan C.K., Chang D.O., Chatterjee K., Chatterjee S., Chen M.T., Chen Y., Cheng X., Cho I., Christian P., Conroy N.S., Conway J.E., Crawford T.M., Crew G.B., Cruz-Osorio A., Dahale R., Davelaar J., De Laurentis M., Deane R., Dempsey J., Desvignes G., Dexter J., Dhruv V., Dihingia I.K., Doeleman S.S., Dzib S.A., Eatough R.P., Emami R., Falcke H., Farah J., Fish V.L., Fomalont E., Ford H.A., Foschi M., Fraga-Encinas R., Freeman W.T., Friberg P., Fromm C.M., Fuentes A., Galison P., Gammie C.F.

Astronomy and Astrophysics Vol. 692 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to γ-ray energies) took part in the second M87 EHT campaign. Aims. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87∗, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity. Methods. The MWL campaign took place in April 2018, overlapping with the EHT M87∗ observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high-energy (VHE) γ-rays as well as details of the individual observations and light curves. We also conducted phenomenological modelling to investigate the basic source properties. Results. We present the first VHE γ-ray flare from M87 detected since 2010. The flux above 350 GeV more than doubled within a period of ≈36 hours.We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image. Conclusions. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE γ-ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and it emphasises the need for combined image and spectral modelling.

DOI： 10.1051/0004-6361/202450497

A new method of reconstructing images of gamma-ray telescopes applied to the LST-1 of CTAO Open Access

Abe, K; Abe, S; Abhishek, A; Acero, F; Aguasca-Cabot, A; Agudo, I; Alispach, C; Crespo, NA; Ambrosino, D; Antonelli, LA; Aramo, C; Arbet-Engels, A; Arcaro, C; Asano, K; Aubert, P; Baktash, A; Balbo, M; Bamba, A; Larriva, AB; de Almeida, UB; Barrio, JA; Jiménez, LB; Batkovic, I; Baxter, J; González, JB; Bernardini, E; Medrano, JB; Berti, A; Bezshyiko, I; Bhattacharjee, P; Bigongiari, C; Bissaldi, E; Blanch, O; Bonnoli, G; Bordas, P; Borkowski, G; Brunelli, G; Bulgarelli, A; Burelli, I; Burmistrov, L; Buscemi, M; Cardillo, M; Caroff, S; Carosi, A; Carrasco, MS; Cassol, F; Castrejón, N; Cauz, D; Cerasole, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chon, G; Chytka, L; Cicciari, GM; Cifuentes, A; Contreras, JL; Cortina, J; Costantini, H; Da Vela, P; Dalchenko, M; Dazzi, F; De Angelis, A; de Lavergne, MD; De Lotto, B; de Menezes, R; Del Burgo, R; Del Peral, L; Delgado, C; Mengual, JD; della Volpe, D; Dellaiera, M; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Díaz, C; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Eisenberger, L; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Ferrarotto, F; Fiasson, A; Foffano, L; Coromina, LF; Fröse, S; Fukazawa, Y; López, RG; Gasbarra, C; Gasparrini, D; Geyer, D; Paiva, JG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, J; Gunji, S; Günther, P; Hackfeld, J; Hadasch, D; Hahn, A; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Iarlori, M; Imazawa, R; Inada, T; Inome, Y; Inoue, S; Ioka, K; Iori, M; Iuliano, A; Martinez, IJ; Quiles, JJ; Jurysek, J; Kagaya, M; Kalashev, O; Karas, V; Katagiri, H; Kataoka, J; Kerszberg, D; Kobayashi, Y; Kohri, K; Kong, A; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Lemoigne, L; Linhoff, M; Longo, F; López-Coto, R; López-Oramas, A; Loporchio, S; Lorini, A; Bahilo, JL; Luciani, H; Luque-Escamilla, PL; Majumdar, P; Makariev, M; Mallamaci, M; Mandat, D; Manganaro, M; Manicò, G; Mannheim, K; Marchesi, S; Mariotti, M; Marquez, P; Marsella, G; Martí, J; Martinez, O; Martínez, G; Martínez, M; Mas-Aguilar, A; Maurin, G; Mazin, D; Méndez-Gallego, J; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Gonzalez, MM; Molina, E; Montaruli, T; Moralejo, A; Morcuende, D; Morselli, A; Moya, V; Muraishi, H; Nagataki, S; Nakamori, T; Neronov, A; Nickel, L; Rosillo, MN; Nikolic, L; Nishijima, K; Noda, K; Nosek, D; Novotny, V; Nozaki, S; Ohishi, M; Ohtani, Y; Oka, T; Okumura, A; Orito, R; Otero-Santos, J; Ottanelli, P; Owen, E; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pech, M; Pecimotika, M; Peresano, M; Pfeifle, F; Pietropaolo, E; Pihet, M; Pirola, G; Plard, C; Podobnik, F; Pons, E; Prandini, E; Priyadarshi, C; Prouza, M; Rainò, S; Rando, R; Rhode, W; Ribó, M; Righi, C; Rizi, V; Fernandez, GR; Frías, MD; Ruina, A; Ruiz-Velasco, E; Saito, T; Sakurai, S; Sanchez, DA; Sano, H; Saric, T; Sato, Y; Saturni, FG; Savchenko, V; Schiavone, F; Schleicher, B; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Arroyo, MS; Siegert, T; Sitarek, J; Sliusar, V; Striskovic, J; Strzys, M; Suda, Y; Tajima, H; Takahashi, H; Takahashi, M; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Tavernier, T; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Travnicek, P; Tutone, A; Vacula, M; Vallania, P; van Scherpenberg, J; Acosta, MV; Ventura, S; Verna, G; Viale, I; Vigliano, A; Vigorito, CF; Visentin, E; Vitale, V; Voitsekhovskyi, V; Voutsinas, G; Vovk, I; Vuillaume, T; Walter, R; Wan, L; Will, M; Wójtowicz, J; Yamamoto, T; Yamazaki, R; Yeung, PKH; Yoshida, T; Yoshikoshi, T; Zhang, W; Zywucka, N

ASTRONOMY & ASTROPHYSICS Vol. 691 2024.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. Imaging atmospheric Cherenkov telescopes (IACTs) are used to observe very high-energy photons from the ground. Gamma rays are indirectly detected through the Cherenkov light emitted by the air showers they induce. The new generation of experiments, in particular the Cherenkov Telescope Array Observatory (CTAO), sets ambitious goals for discoveries of new gamma-ray sources and precise measurements of the already discovered ones. To achieve these goals, both hardware and data analysis must employ cutting-edge techniques. This also applies to the LST-1, the first IACT built for the CTAO, which is currently taking data on the Canary island of La Palma. Aims. This paper introduces a new event reconstruction technique for IACT data, aiming to improve the image reconstruction quality and the discrimination between the signal and the background from misidentified hadrons and electrons. Methods. The technique models the development of the extensive air shower signal, recorded as a waveform per pixel, seen by CTAO telescopes’ cameras. Model parameters are subsequently passed to random forest regressors and classifiers to extract information on the primary particle. Results. The new reconstruction was applied to simulated data and to data from observations of the Crab Nebula performed by the LST-1. The event reconstruction method presented here shows promising performance improvements. The angular and energy resolution, and the sensitivity, are improved by 10 to 20% over most of the energy range. At low energy, improvements reach up to 22%, 47%, and 50%, respectively. A future extension of the method to stereoscopic analysis for telescope arrays will be the next important step.

DOI： 10.1051/0004-6361/202450889

Standardised formats and open-source analysis tools for the MAGIC telescopes data Open Access

Abe, S; Abhir, J; Abhishek, A; Acciari, VA; Aguasca-Cabot, A; Agudo, I; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Artero, M; Asano, K; Babic, A; de Almeida, UB; Barrio, JA; Batkovic, I; Bautista, A; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Bronzini, E; Burelli, I; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Cerasole, D; Ceribella, G; Chai, Y; Cifuentes, A; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; de Menezes, R; Delfino, M; Delgado, J; Di Pierro, F; Di Tria, R; Di Venere, L; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fröse, S; Fukami, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Gradetzke, T; Grau, R; Green, D; Green, JG; Günther, P; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Llorente, JH; Hrupec, D; Hütten, M; Imazawa, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kayanoki, T; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Láinez, M; Lamastra, A; Leone, F; Lindfors, E; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Lyard, E; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Martínez-Chicharro, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nakamori, T; Nanci, C; Neustroev, V; Nickel, L; Rosillo, MN; Nigro, C; Nikolic, L; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Paneque, D; Paoletti, R; Paredes, JM; Peresano, M; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Saturni, FG; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Silvestri, G; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Tajima, H; Takahashi, M; Takeishi, R; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Viale, I; Vigorito, CF; Vitale, V; Vovk, I; Walter, R; Will, M; Wunderlich, C; Yamamoto, T; Jouvin, L; Linhoff, L; Linhoff, M

JOURNAL OF HIGH ENERGY ASTROPHYSICS Vol. 44 page： 266 - 278 2024.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of High Energy Astrophysics

Instruments for gamma-ray astronomy at Very High Energies (E>100GeV) have traditionally derived their scientific results through proprietary data and software. Data standardisation has become a prominent issue in this field both as a requirement for the dissemination of data from the next generation of gamma-ray observatories and as an effective solution to realise public data legacies of current-generation instruments. Specifications for a standardised gamma-ray data format have been proposed as a community effort and have already been successfully adopted by several instruments. We present the first production of standardised data from the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We converted 166h of observations from different sources and validated their analysis with the open-source software Gammapy. We consider six data sets representing different scientific and technical analysis cases and compare the results obtained analysing the standardised data with open-source software against those produced with the MAGIC proprietary data and software. Aiming at a systematic production of MAGIC data in this standardised format, we also present the implementation of a database-driven pipeline automatically performing the MAGIC data reduction from the calibrated down to the standardised data level. In all the cases selected for the validation, we obtain results compatible with the MAGIC proprietary software, both for the manual and for the automatic data productions. Part of the validation data set is also made publicly available, thus representing the first large public release of MAGIC data. This effort and this first data release represent a technical milestone toward the realisation of a public MAGIC data legacy.

DOI： 10.1016/j.jheap.2024.09.011

A detailed study of the very high-energy Crab pulsar emission with the LST-1 Open Access

Abe, K; Abe, S; Abhishek, A; Acero, F; Aguasca-Cabot, A; Agudo, ; Crespo, NA; Antonelli, LA; Aramo, C; Arbet-Engels, A; Arcaro, C; Artero, M; Asano, K; Aubert, P; Baktash, A; Bamba, A; Larriva, AB; Baroncelli, L; de Almeida, UB; Barrio, JA; Batkovic, ; Baxter, J; Gonzailez, JB; Bernardini, E; Medrano, JB; Berti, A; Bhattacharjee, P; Bigongiari, C; Bissaldi, E; Blanch, O; Bonnoli, G; Bordas, P; Brunelli, G; Bulgarelli, A; Burelli, ; Burmistrov, L; Buscemi, M; Cardillo, M; Caroff, S; Carosi, A; Carrasco, MS; Cassol, F; Castrejón, N; Cauz, D; Cerasole, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chon, G; Chytka, L; Cicciari, GM; Cifuentes, A; Contreras, JL; Cortina, J; Costantini, H; Da Vela, P; Dalchenko, M; Dazzi, F; De Angelis, A; de Lavergne, MD; De Lotto, B; de Menezes, R; Del Peral, L; Delgado, C; Mengual, JD; della Volpe, D; Dellaiera, M; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Díaz, C; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Eisenberger, L; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Ferrarotto, F; Fiasson, A; Foffano, L; Coromina, LF; Fröse, S; Fukazawa, Y; López, RG; Gasbarra, C; Gasparrini, D; Gavira, L; Geyer, D; Paiva, JG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, J; Gunji, S; Günther, P; Hackfeld, J; Hadasch, D; Hahn, A; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Iarlori, M; Imazawa, R; Inada, T; Inome, Y; Ioka, K; Iori, M; Martinez, IJ; Quiles, JJ; Jurysek, J; Kagaya, M; Karas, ; Katagiri, H; Kataoka, J; Kerszberg, D; Kobayashi, Y; Kohri, K; Kong, A; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Lemoigne, L; Linhoff, M; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Bahilo, JL; Luque-Escamilla, PL; Majumdar, P; Makariev, M; Mallamaci, M; Mandat, D; Manganaro, M; Manicò, G; Mannheim, K; Marchesi, S; Mariotti, M; Marquez, P; Marsella, G; Martí, J; Martinez, O; Martínez, G; Martínez, M; Mas-Aguilar, A; Maurin, G; Mazin, D; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Gonzalez, MM; Molina, E; Montaruli, T; Moralejo, A; Morcuende, D; Morselli, A; Moya, ; Muraishi, H; Nagataki, S; Nakamori, T; Neronov, A; Nickel, L; Rosillo, MN; Nikolic, L; Nishijima, K; Noda, K; Nosek, D; Novotny, ; Nozaki, S; Ohishi, M; Ohtani, Y; Oka, T; Okumura, A; Orito, R; Otero-Santos, J; Ottanelli, P; Owen, E; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pech, M; Pecimotika, M; Peresano, M; Pfeiffle, F; Pietropaolo, E; Pihet, M; Pirola, G; Plard, C; Podobnik, F; Pons, E; Prandini, E; Priyadarshi, C; Prouza, M; Rando, R; Rhode, W; Ribó, M; Righi, C; Rizi, ; Fernandez, GR; Frias, MDR; Saito, T; Sakurai, S; Sanchez, DA; Sano, H; Saric, T; Sato, Y; Saturni, FG; Savchenko, ; Schiavone, F; Schleicher, B; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Arroyo, MS; Siegert, T; Silvia, R; Sitarek, J; Sliusar, ; Striskovic, J; Strzys, M; Suda, Y; Tajima, H; Takahashi, H; Takahashi, M; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Tavernier, T; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Travnicek, P; Truzzi, S; Tutone, A; Vacula, M; Vallania, P; van Scherpenberg, J; Acosta, MV; Verna, G; Viale, ; Vigliano, A; Vigorito, CF; Visentin, E; Vitale, V; Voitsekhovskyi, V; Voutsinas, G; Vovk, ; Vuillaume, T; Walter, R; Wan, L; Will, M; Yamamoto, T; Yamazaki, R; Yeung, PKH; Yoshida, T; Yoshikoshi, T; Zhang, W; Zywucka, N

ASTRONOMY & ASTROPHYSICS Vol. 690 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. To date, three pulsars have been firmly detected by imaging atmospheric Cherenkov telescopes (IACTs). Two of them reached the TeV energy range, challenging models of very high-energy (VHE) emission in pulsars. More precise observations are needed to better characterize pulsar emission at these energies. The LST-1 is the prototype of the large-sized telescopes, which will be part of the Cherenkov Telescope Array Observatory (CTAO). Its improved performance over previous IACTs makes it well suited for studying pulsars. Aims. In this work we study the Crab pulsar emission with the LST-1, improving upon and complementing the results from other telescopes. Crab pulsar observations can also be used to characterize the potential of the LST-1 to study other pulsars and detect new ones. Methods. We analyzed a total of ~103 hours of gamma-ray observations of the Crab pulsar conducted with the LST-1 in the period from September 2020 to January 2023. The observations were carried out at zenith angles of less than 50 degrees. To characterize the Crab pulsar emission over a broader energy range, a new analysis of the Fermi/LAT data, including ~14 years of observations, was also performed. Results. The Crab pulsar phaseogram, long-term light curve, and phase-resolved spectra are reconstructed with the LST-1 from 20 GeV to 450 GeV for the first peak and up to 700 GeV for the second peak The pulsed emission is detected with a significance level of 15.2σ. The two characteristic emission peaks of the Crab pulsar are clearly detected (> 10σ), as is the so-called bridge emission between them (5.7σ). We find that both peaks are described well by power laws, with spectral indices of ~3.44 and ~3.03, respectively. The joint analysis of Fermi/LAT and LST-1 data shows a good agreement between the two instruments in their overlapping energy range. The detailed results obtained from the first observations of the Crab pulsar with the LST-1 show the potential that CTAO will have to study this type of source.

DOI： 10.1051/0004-6361/202450059

Prospects for a survey of the galactic plane with the Cherenkov Telescope Array

Abe, S; Abhir, J; Abhishek, A; Acero, F; Acharyya, A; Adam, R; Aguasca-Cabot, A; Agudo, I; Aguirre-Santaella, A; Alfaro, J; Alvarez-Crespo, N; Batista, RA; Amans, JP; Amato, E; Ambrosi, G; Ambrosino, F; Angüner, EO; Aramo, C; Arcaro, C; Arrabito, L; Asano, K; Ascasíbar, Y; Aschersleben, J; Stuani, LA; Backes, M; Balazs, C; Balbo, M; Ballet, J; Larriva, AB; Martins, VB; de Almeida, UB; Barrio, JA; Batkovic, I; Batzofin, R; Baxter, J; González, JB; Beck, G; Beiske, L; Belmont, R; Benbow, W; Bernardini, E; Bernete, J; Bernlöhr, K; Berti, A; Bertucci, B; Beshley, V; Bhattacharjee, P; Bhattacharyya, S; Bi, B; Biederbeck, N; Biland, A; Bissaldi, E; Biteau, J; Blanch, O; Blazek, J; Bocchino, F; Boisson, C; Bolmont, J; Arbeletche, LB; Bonnoli, G; Bonollo, A; Bordas, P; Bosnjak, Z; Bottacini, E; Braiding, C; Bronzini, E; Brose, R; Brown, AM; Brun, F; Brunelli, G; Bucciantini, N; Bulgarelli, A; Burelli, I; Burmistrov, L; Burton, M; Burtovoi, A; Bylund, T; Calisse, PG; Campoy-Ordaz, A; Cantlay, BK; Caproni, A; Capuzzo-Dolcetta, R; Caraveo, P; Caroff, S; Carosi, A; Carosi, R; Carquin, E; Carrasco, MS; Cascone, E; Cassol, F; Castrejon, N; Castro-Tirado, AJ; Cerasole, D; Cerruti, M; Chadwick, PM; Chambery, P; Chaty, S; Chen, AW; Chernyakova, M; Chiavassa, A; Chytka, L; Cifuentes, A; Araujo, CHC; Conforti, V; Conte, F; Contreras, JL; Cortina, J; Costa, A; Costantini, H; Cotter, G; Crestan, S; Cristofari, P; Cuevas, O; Curtis-Ginsberg, Z; D'Aì, A; D'Amico, G; D'Ammando, F; Dadina, M; Dalchenko, M; David, L; Dazzi, F; de Lavergne, MD; De Caprio, V; Laadim, FD; Dal Pino, EMD; De Lotto, B; De Lucia, M; de Martino, D; de Menezes, R; de Naurois, M; Wilhelmi, ED; de Souza, V; del Peral, L; Giler, AGD; Delgado, C; Dell'aiera, M; Della Valle, M; della Volpe, D; Depaoli, D; Di Girolamo, T; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Díaz, C; Diebold, S; Dinesh, A; Djannati-Ataï, A; Djuvsland, J; Domínguez, A; Dominik, RM; Donini, A; Dörner, J; Doro, M; dos Anjos, RDC; Dournaux, JL; Duangchan, C; Dubos, C; Dubus, G; Duffy, S; Dumora, D; Dwarkadas, VV; Ebr, J; Eckner, C; Egberts, K; Einecke, S; Elsässer, D; Emery, G; Errando, M; Escanuela, C; Escarate, P; Godoy, ME; Escudero, J; Esposito, P; Evoli, C; Falceta-Goncalves, D; Fattorini, A; Fegan, S; Feijen, K; Feng, Q; Ferrand, G; Ferrarotto, F; Fiandrini, E; Fiasson, A; Filipovic, M; Fioretti, V; Fiori, M; Flores, H; Foffano, L; Guiteras, LF; Fontaine, G; Fröse, S; Fukazawa, Y; Fukui, Y; Funk, S; Furniss, A; Gaggero, D; Galanti, G; Galaz, G; Gallant, YA; Gallozzi, S; Gammaldi, V; Garczarczyk, M; Gasbarra, C; Gasparrini, D; Gaug, M; Ghalumyan, A; Giarrusso, M; Giesbrecht, J; Giglietto, N; Giordano, F; Giuffrida, R; Giuliani, A; Glicenstein, JF; Glombitza, J; Godinovic, N; Goldoni, P; González, JM; Coelho, JG; Granot, J; Grasso, D; Grau, R; Gréaux, L; Green, D; Green, JG; Greenshaw, T; Grenier, I; Grolleron, G; Grondin, MH; Gueta, O; Gunji, S; Hackfeld, J; Hadasch, D; Hanlon, W; Hara, S; Harvey, VM; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Hermann, G; Cadena, SH; Hervet, O; Hinton, J; Hiroshima, N; Hnatyk, B; Hnatyk, R; Hofmann, W; Holder, J; Holler, M; Horan, D; Horvath, P; Hovatta, T; Hrabovsky, M; Iarlori, M; Inada, T; Incardona, F; Inoue, S; Iocco, F; Iori, M; Jamrozy, M; Janecek, P; Jankowsky, F; Jarnot, C; Jean, P; Martínez, IJ; Jin, W; Juramy-Gilles, C; Jurysek, J; Kagaya, M; Kalekin, O; Kantzas, D; Karas, V; Katagiri, H; Kataoka, J; Kaufmann, S; Kazanas, D; Kerszberg, D; Khélifi, B; Kieda, DB; Kissmann, R; Kleiner, T; Kluge, G; Kluzniak, W; Knödlseder, J; Kobayashi, Y; Kohri, K; Komin, N; Kornecki, P; Kosack, K; Kostunin, D; Kowal, G; Kubo, H; Kushida, J; La Barbera, A; La Palombara, N; Láinez, M; Lamastra, A; Lapington, J; Laporte, P; Lazarevic, S; Lazendic-Galloway, J; Lemoine-Goumard, M; Lenain, JP; Leone, F; Leto, G; Leuschner, F; Lindfors, E; Linhoff, M; Liodakis, I; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Bahilo, JL; Lucarelli, F; Luque-Escamilla, PL; Lyard, E; Macias, O; Mackey, J; Maier, G; Malyshev, D; Mandat, D; Manicò, G; Marcowith, A; Marinos, P; Mariotti, M; Markoff, S; Marquez, P; Marsella, G; Martí, J; Martin, P; Martínez, GA; Martínez, M; Martinez, O; Marty, C; Mas-Aguilar, A; Mastropietro, M; Maurin, G; Mazin, D; McKeague, S; Mello, AJTS; Menchiari, S; Mereghetti, S; Mestre, E; Meunier, JL; Meyer, DMA; Miceli, D; Miceli, M; Michailidis, M; Michalowski, J; Miener, T; Miranda, JM; Mitchell, A; Mizuno, T; Moderski, R; Mohrmann, L; Molero, M; Molfese, C; Molina, E; Montaruli, T; Moralejo, A; Morcuende, D; Morik, K; Morlino, G; Morselli, A; Moulin, E; Zamanillo, VM; Mukherjee, R; Munari, K; Murach, T; Muraczewski, A; Muraishi, H; Nagataki, S; Nakamori, T; Nemmen, R; Nickel, L; Niemiec, J; Nieto, D; Rosillo, MN; Nikolajuk, M; Nikolic, L; Noda, K; Nosek, D; Novosyadlyj, B; Novotny, V; Nozaki, S; Ohishi, M; Ohtani, Y; Okumura, A; Olive, JF; Olmi, B; Ong, RA; Orienti, M; Orito, R; Orlandini, M; Orlando, E; Orlando, S; Ostrowski, M; Oya, I; Pagano, I; Pagliaro, A; Palatiello, M; Panebianco, G; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Parmiggiani, N; Patel, SR; Patricelli, B; Pavlovic, D; Pech, M; Pecimotika, M; Peresano, M; Pérez-Romero, J; Pérez-Torres, MA; Peron, G; Persic, M; Petrucci, PO; Petruk, O; Piano, G; Pierre, E; Pietropaolo, E; Pihet, M; Pintore, F; Pittori, C; Plard, C; Podobnik, F; Pohl, M; Pons, E; Ponti, G; Prandini, E; Principe, G; Priyadarshi, C; Produit, N; Prokhorov, D; Pueschel, E; Pühlhofer, G; Pumo, ML; Punch, M; Queiroz, F; Quirrenbach, A; Rando, R; Ravel, T; Razzaque, S; Regeard, M; Reichherzer, P; Reimer, A; Reimer, O; Remy, Q; Renaud, M; Reposeur, T; Rhode, W; Ribeiro, D; Ribó, M; Richtler, T; Rico, J; Rieger, F; Rigoselli, M; Rizi, V; Roache, E; Fernandez, GR; Rodríguez-Vázquez, JJ; Romano, P; Romeo, G; Rosado, J; de Leon, AR; Rowell, G; Rudak, B; Ruiter, AJ; Rulten, CB; Russo, F; Sadeh, I; Saha, L; Saito, T; Salzmann, H; Sánchez-Conde, M; Sangiorgi, P; Sano, H; Santander, M; Santangelo, A; Santos-Lima, R; Sapienza, V; Saric, T; Sarkar, S; Saturni, FG; Scherer, A; Schiavone, F; Schipani, P; Schleicher, B; Schovanek, P; Schubert, JL; Schussler, F; Schwanke, U; Schwefer, G; Arroyo, MS; Seitenzahl, I; Sergijenko, O; Servillat, M; Sguera, V; Sharma, P; Siejkowski, H; Siqueira, C; Sizun, P; Sliusar, V; Slowikowska, A; Sol, H; Spencer, ST; Spiga, D; Stamerra, A; Stanic, S; Starling, R; Stawarz, L; Steinmassl, S; Steppa, C; Stolarczyk, T; Suda, Y; Suomijärvi, T; Tajima, H; Takeishi, R; Tanaka, SJ; Tavecchio, F; Tavernier, T; Terada, Y; Terrier, R; Teshima, M; Tian, WW; Tibaldo, L; Tibolla, O; Torradeflot, F; Torres, DF; Tothill, N; Toussenel, F; Touzard, V; Travnicek, P; Tripodo, G; Trois, A; Tsiahina, A; Tutone, A; Umana, G; Vaclavek, L; Vacula, M; Vallania, P; van Eldik, C; Vassiliev, V; Acosta, MLV; Vecchi, M; Ventura, S; Vercellone, S; Verna, G; Viana, A; Viaux, N; Vigliano, A; Vignatti, J; Vigorito, CF; Villanueva, J; Vink, J; Vitale, V; Vodeb, V; Voisin, V; Vorobiov, S; Voutsinas, G; Vovk, I; Vuillaume, T; Waegebaert, V; Wagner, SJ; Walter, R; Wechakama, M; White, R; Wierzcholska, A; Williams, DA; Wohlleben, F; Yamazaki, R; Yang, L; Yoshida, T; Yoshikoshi, T; Zacharias, M; Zaharijas, G; Zampieri, L; Zanin, R; Zavrtanik, D; Zavrtanik, M; Zdziarski, AA; Zech, A; Zhdanov, VI; Zietara, K; Zivec, M; Zuriaga-Puig, J; Luque, PD; Guillemot, L; Smith, DA

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Vol. 2024 ( 10 ) 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Cosmology and Astroparticle Physics

Approximately one hundred sources of very-high-energy (VHE) gamma rays are known in the Milky Way, detected with a combination of targeted observations and surveys. A survey of the entire Galactic Plane in the energy range from a few tens of GeV to a few hundred TeV has been proposed as a Key Science Project for the upcoming Cherenkov Telescope Array Observatory (CTAO). This article presents the status of the studies towards the Galactic Plane Survey (GPS). We build and make publicly available a sky model that combines data from recent observations of known gamma-ray emitters with state-of-the-art physically-driven models of synthetic populations of the three main classes of established Galactic VHE sources (pulsar wind nebulae, young and interacting supernova remnants, and compact binary systems), as well as of interstellar emission from cosmic-ray interactions in the Milky Way. We also perform an optimisation of the observation strategy (pointing pattern and scheduling) based on recent estimations of the instrument performance. We use the improved sky model and observation strategy to simulate GPS data corresponding to a total observation time of 1620 hours spread over ten years. Data are then analysed using the methods and software tools under development for real data. Under our model assumptions and for the realisation considered, we show that the GPS has the potential to increase the number of known Galactic VHE emitters by almost a factor of five. This corresponds to the detection of more than two hundred pulsar wind nebulae and a few tens of supernova remnants at average integral fluxes one order of magnitude lower than in the existing sample above 1 TeV, therefore opening the possibility to perform unprecedented population studies. The GPS also has the potential to provide new VHE detections of binary systems and pulsars, to confirm the existence of a hypothetical population of gamma-ray pulsars with an additional TeV emission component, and to detect bright sources capable of accelerating particles to PeV energies (PeVatrons). Furthermore, the GPS will constitute a pathfinder for deeper follow-up observations of these source classes. Finally, we show that we can extract from GPS data an estimate of the contribution to diffuse emission from unresolved sources, and that there are good prospects of detecting interstellar emission and statistically distinguishing different scenarios. Thus, a survey of the entire Galactic plane carried out from both hemispheres with CTAO will ensure a transformational advance in our knowledge of Galactic VHE source populations and interstellar emission.

DOI： 10.1088/1475-7516/2024/10/081

Prospects for γ-ray observations of the Perseus galaxy cluster with the Cherenkov Telescope Array Open Access

Abe, K; Abe, S; Acero, F; Acharyya, A; Adam, R; Aguasca-Cabot, A; Agudo, I; Aguirre-Santaella, A; Alfaro, J; Alfaro, R; Alvarez-Crespo, N; Batista, RA; Amans, JP; Amato, E; Angüner, EO; Antonelli, LA; Aramo, C; Araya, M; Arcaro, C; Arrabito, L; Asano, K; Ascasíbar, Y; Aschersleben, J; Ashkar, H; Stuani, LA; Baack, D; Backes, M; Baktash, A; Balazs, C; Balbo, M; Ballester, O; Larriva, AB; Martins, VB; de Almeida, UB; Barrio, JA; Batista, PI; Batkovic, I; Batzofin, R; Baxter, J; González, JB; Beck, G; Tjus, JB; Benbow, W; Medrano, JB; Bernlöhr, K; Berti, A; Bertucci, B; Beshley, V; Bhattacharjee, P; Bhattacharyya, S; Bi, B; Biederbeck, N; Biland, A; Bissaldi, E; Biteau, J; Blanch, O; Blazek, J; Boisson, C; Bolmont, J; Bordas, P; Bosnjak, Z; Bottacini, E; Bradascio, F; Braiding, C; Bronzini, E; Brose, R; Brown, AM; Brun, F; Brunetti, G; Bucciantini, N; Bulgarelli, A; Burelli, I; Burmistrov, L; Burton, M; Bylund, T; Calisse, PG; Campoy-Ordaz, A; Cantlay, BK; Capalbi, M; Caproni, A; Capuzzo-Dolcetta, R; Caraveo, P; Caroff, S; Carosi, R; Carquin, E; Carrasco, MS; Cascone, E; Cassol, F; Castro-Tirado, AJ; Cerasole, D; Cerruti, M; Chadwick, P; Chaty, S; Chen, AW; Chernyakova, M; Chiavassa, A; Chudoba, J; Chytka, L; Cifuentes, A; Araujo, CHC; Conforti, V; Conte, F; Contreras, JL; Cortina, J; Costa, A; Costantini, H; Cotter, G; Cristofari, P; Cuevas, O; Curtis-Ginsberg, Z; D'Amico, G; D'Ammando, F; Dalchenko, M; Dazzi, F; de Lavergne, MD; De Caprio, V; Laadim, FDF; Dal Pino, EMD; De Lotto, B; De Lucia, M; De Martino, D; De Menezes, R; de Naurois, M; De Simone, N; De Souza, V; del Valle, MV; Delagnes, E; Giler, AGD; Delgado, C; Dell'aiera, M; della Volpe, D; Depaoli, D; Di Girolamo, T; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Diebold, S; Djannati-Ataï, A; Djuvsland, J; Dominik, RM; Donini, A; Dorner, D; Dörner, J; Doro, M; dos Anjos, RDC; Dournaux, JL; Duangchan, C; Dubos, C; Dumora, D; Dwarkadas, VV; Ebr, J; Eckner, C; Egberts, K; Einecke, S; Elsässer, D; Emery, G; Godoy, ME; Escudero, J; Esposito, P; Ettori, S; Evoli, C; Falceta-Goncalves, D; Ramazani, VF; Fattorini, A; Faure, A; Fedorova, E; Fegan, S; Feijen, K; Feng, Q; Ferrand, G; Ferrarotto, F; Fiandrini, E; Fiasson, A; Filipovic, M; Fioretti, V; Foffano, L; Guiteras, LF; Fontaine, G; Fröse, S; Fukazawa, Y; Fukui, Y; Gaggero, D; Galanti, G; Gallozzi, S; Gammaldi, V; Garczarczyk, M; Gasbarra, C; Gasparrini, D; Gaug, M; Ghalumyan, A; Gianotti, F; Giarrusso, M; Giesbrecht, J; Giglietto, N; Giordano, F; Glicenstein, JF; Göksu, H; Goldoni, P; González, JM; González, MM; Coelho, JG; Granot, J; Grau, R; Gréaux, L; Green, D; Green, JG; Grenier, I; Grolleron, G; Grube, J; Gueta, O; Hackfeld, J; Hadasch, D; Hamal, P; Hanlon, W; Hara, S; Harvey, VM; Hassan, T; Heckmann, L; Heller, M; Cadena, SH; Hervet, O; Hie, J; Hiroshima, N; Hnatyk, B; Hnatyk, R; Hoang, J; Hoffmann, D; Hofmann, W; Holder, J; Horan, D; Horvath, P; Hrupec, D; Hütten, M; Iarlori, M; Inada, T; Incardona, F; Inoue, S; Iocco, F; Iori, M; Jamrozy, M; Janecek, P; Jankowsky, F; Jarnot, C; Jean, P; Martínez, IJ; Jin, W; Juramy-Gilles, C; Jurysek, J; Kagaya, M; Kantzas, D; Karas, V; Katagiri, H; Kataoka, J; Kaufmann, S; Kerszberg, D; Khélifi, B; Kissmann, R; Kleiner, T; Kluge, G; Kluzniak, W; Knödlseder, J; Kobayashi, Y; Kohri, K; Komin, N; Kornecki, P; Kosack, K; Kowal, G; Kubo, H; Kushida, J; La Barbera, A; La Palombara, N; Láinez, M; Lamastra, A; Lapington, J; Laporte, P; Lazarevic, S; Leitgeb, F; Lemoine-Goumard, M; Lenain, JP; Leone, F; Leto, G; Leuschner, F; Lindfors, E; Linhoff, M; Liodakis, I; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Luque-Escamilla, PL; Macias, O; Mackey, J; Majumdar, P; Malyshev, D; Mandat, D; Manganaro, M; Manicò, G; Mariotti, M; Markoff, S; Márquez, I; Marquez, P; Marsella, G; Martínez, GA; Martínez, M; Martinez, O; Marty, C; Mas-Aguilar, A; Mastropietro, M; Maurin, G; Mazin, D; Melkumyan, D; Mello, AJTS; Meunier, JL; Meyer, DMA; Meyer, M; Miceli, D; Michailidis, M; Michalowski, J; Miener, T; Miranda, JM; Mitchell, A; Mizote, M; Mizuno, T; Moderski, R; Molero, M; Molfese, C; Molina, E; Montaruli, T; Morcuende, D; Morik, K; Morlino, G; Morselli, A; Moulin, E; Zamanillo, VM; Munari, K; Murach, T; Muraczewski, A; Muraishi, H; Nagataki, S; Nakamori, T; Nemmen, R; Neyroud, N; Nickel, L; Niemiec, J; Nieto, D; Rosillo, MN; Nikolajuk, M; Nishijima, K; Noda, K; Nosek, D; Novotny, V; Nozaki, S; O'Brien, P; Ohishi, M; Ohtani, Y; Okumura, A; Olive, JF; Olmi, B; Ong, RA; Orienti, M; Orito, R; Orlandini, M; Orlando, E; Ostrowski, M; Oya, I; Pagliaro, A; Palatiello, M; Panebianco, G; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Parmiggiani, N; Patel, SR; Patricelli, B; Pavlovic, D; Pech, M; Pecimotika, M; Pensec, U; Peresano, M; Pérez-Romero, J; Peron, G; Persic, M; Petrucci, PO; Petruk, O; Piano, G; Pierre, E; Pietropaolo, E; Pintore, F; Pirola, G; Pita, S; Plard, C; Podobnik, F; Pohl, M; Polo, M; Pons, E; Ponti, G; Prandini, E; Prast, J; Principe, G; Priyadarshi, C; Produit, N; Pueschel, E; Pühlhofer, G; Pumo, ML; Punch, M; Queiroz, F; Quirrenbach, A; Rainò, S; Rando, R; Razzaque, S; Recchia, S; Regeard, M; Reichherzer, P; Reimer, A; Reimer, O; Reisenegger, A; Rhode, W; Ribeiro, D; Ribó, M; Richtler, T; Rico, J; Rieger, F; Righi, C; Riitano, L; Rizi, V; Roache, E; Fernandez, GR; Rodríguez-Vázquez, JJ; Romano, P; Romeo, G; Rosado, J; de Leon, AR; Rowell, G; Rudak, B; Rulten, CB; Russo, F; Sadeh, I; Saha, L; Saito, T; Salzmann, H; Sanchez, D; Sánchez-Conde, M; Sangiorgi, P; Sano, H; Santander, M; Santangelo, A; Santos-Lima, R; Sanuy, A; Saric, T; Sarkar, A; Sarkar, S; Satalecka, K; Saturni, FG; Savchenko, V; Scherer, A; Schipani, P; Schleicher, B; Schubert, JL; Schussler, F; Schwanke, U; Schwefer, G; Arroyo, MS; Seiji, S; Semikoz, D; Sergijenko, O; Servillat, M; Sguera, V; Shang, RY; Sharma, P; Siejkowski, H; Sinha, A; Siqueira, C; Sliusar, V; Slowikowska, A; Sol, H; Specovius, A; Spencer, ST; Spiga, D; Stamerra, A; Stanic, S; Starecki, T; Starling, R; Stawarz, L; Steppa, C; Stolarczyk, T; Striskovic, J; Suda, Y; Suomijärvi, T; Tajima, H; Tak, D; Takahashi, M; Takeishi, R; Tanaka, SJ; Tavernier, T; Tejedor, LA; Terauchi, K; Terrier, R; Teshima, M; Tian, WW; Tibaldo, L; Tibolla, O; Torradeflot, F; Torres, DF; Torresi, E; Tosti, G; Tosti, L; Tothill, N; Toussenel, F; Touzard, V; Tramacere, A; Travnicek, P; Tripodo, G; Truzzi, S; Tsiahina, A; Tutone, A; Vacula, M; Vallage, B; Vallania, P; van Eldik, C; van Scherpenberg, J; Vandenbroucke, J; Vassiliev, V; Acosta, MV; Vecchi, M; Ventura, S; Vercellone, S; Verna, G; Viana, A; Viaux, N; Vigliano, A; Vigorito, CF; Vitale, V; Vodeb, V; Voisin, V; Vorobiov, S; Voutsinas, G; Vovk, I; Vuillaume, T; Wagner, SJ; Walter, R; Wechakama, M; White, R; Wierzcholska, A; Will, M; Williams, DA; Wohlleben, F; Wolter, A; Yamamoto, T; Yamazaki, R; Yoshida, T; Yoshikoshi, T; Zacharias, M; Zaharijas, G; Zavrtanik, D; Zavrtanik, M; Zdziarski, AA; Zech, A; Zhdanov, VI; Zivec, M; Zuriaga-Puig, J; Luque, PD

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Vol. 2024 ( 10 ) 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Cosmology and Astroparticle Physics

Galaxy clusters are expected to be both dark matter (DM) reservoirs and storage rooms for the cosmic-ray protons (CRp) that accumulate along the cluster’s formation history. Accordingly, they are excellent targets to search for signals of DM annihilation and decay at γ-ray energies and are predicted to be sources of large-scale γ-ray emission due to hadronic interactions in the intracluster medium (ICM). In this paper, we estimate the sensitivity of the Cherenkov Telescope Array (CTA) to detect diffuse γ-ray emission from the Perseus galaxy cluster. We first perform a detailed spatial and spectral modelling of the expected signal for both the DM and the CRp components. For each case, we compute the expected CTA sensitivity accounting for the CTA instrument response functions. The CTA observing strategy of the Perseus cluster is also discussed. In the absence of a diffuse signal (non-detection), CTA should constrain the CRp to thermal energy ratio X500 within the characteristic radius R500 down to about X500 < 3 × 10−3, for a spatial CRp distribution that follows the thermal gas and a CRp spectral index αCRp = 2.3. Under the optimistic assumption of a pure hadronic origin of the Perseus radio mini-halo and depending on the assumed magnetic field profile, CTA should measure αCRp down to about ∆αCRp ≃ 0.1 and the CRp spatial distribution with 10% precision, respectively. Regarding DM, CTA should improve the current ground-based γ-ray DM limits from clusters observations on the velocity-averaged annihilation cross-section by a factor of up to ∼ 5, depending on the modelling of DM halo substructure. In the case of decay of DM particles, CTA will explore a new region of the parameter space, reaching models with τχ > 1027 s for DM masses above 1 TeV. These constraints will provide unprecedented sensitivity to the physics of both CRp acceleration and transport at cluster scale and to TeV DM particle models, especially in the decay scenario.

DOI： 10.1088/1475-7516/2024/10/004

A survey to evaluate diversity, equity and inclusion in large collaborations

van Scherpenberg J., Heckmann L., Strišković J., Berti A., Dorner D., Elsaesser D., Green J., Manganaro M., Satalecka K., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Doro M., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Herrera J., Hrupec D., Hütten M., Imazawa R.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

In 2020, the MAGIC collaboration started an initiative to improve diversity, equity and inclusion (DEI) in the collaboration. One of the major actions undertaken by this initiative was a survey which was distributed among all MAGIC members with the goal of getting a clear picture of the status quo and to identify potential problems or opportunities concerning DEI related topics. Two surveys have since been performed - one in December 2020 and one in June 2022 - covering questions related to demographics, working conditions, recognition, harassment, bullying and discrimination. In this contribution, we present the questionnaire and strategy used to run these surveys. Additionally, we describe the impact the survey had within the collaboration and which actions have been taken as a direct consequence of the survey results.

Improvement of the follow-up observations of IceCube neutrinos by CTA LST

Noda K., Artero M., Fiasson A., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D., Giesbrecht Paiva J., Giglietto N.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

A decade has passed since high-energy astrophysical neutrinos have been discovered by IceCube, however the corresponding sources have not been fully identified yet. The reported coincidence of the high-energy IceCube-170922A with the gamma-ray blazar TXS 0506+056 is not enough to claim that blazars are the dominant high-energy neutrino emitters in the Universe. In fact, recently IceCube announced a second correlation with NGC 1068, a nearby Seyfert galaxy, which is significantly different from a gamma-emitting blazars. The hunt for counterparts of the IceCube neutrinos using gamma-ray telescopes started in 2012. Nonetheless, these efforts will continue with the next-generation gamma-ray telescopes, such as the CTA Large Size Telescopes (LSTs) and other telescopes, by means of an improved and revised observation strategy. These new observations will allow us to detect enough sources in order to elucidate the mystery of the neutrino emitters. In this contribution, we introduces the efforts made thus far in the search for gamma-ray counterpart of high-energy IceCube events using the current generation IACTs, focusing on alerts made of multiple neutrinos events, and present an idea to improve in the observational strategies with the CTA LSTs that will become operational in the coming decade. We will discuss how to reduce the bias to gamma-ray emitters in order to search for possible neutrino counterparts.

Imaging Atmospheric Cherenkov Telescopes pointing determination using the trajectories of the stars in the field of view.

Dalchenko M., Heller M., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D., Giesbrecht Paiva J., Giglietto N., Giordano F.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

We present a new approach to the pointing determination of Imaging Atmospheric Cherenkov Telescopes (IACTs). This method is universal and can be applied to any IACT with minor modifications. It uses the trajectories of the stars in the field of view of the IACT’s main camera and requires neither dedicated auxiliary hardware nor a specific data taking mode. The method consists of two parts: firstly, we reconstruct individual star positions as a function of time, taking into account the point spread function of the telescope; secondly, we perform a simultaneous fit of all reconstructed star trajectories using the orthogonal distance regression method. The method does not assume any particular star trajectories, does not require a long integration time, and can be applied to any IACT observation mode. The performance of the method is assessed with commissioning data of the Large-Sized Telescope prototype (LST-1), showing the method’s stability and remarkable pointing performance of the LST-1 telescope.

Highlights of Galactic Science with the MAGIC telescopes

Strzys M.C., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K., Jiménez Martínez I., Jormanainen J.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

There are several types of Galactic sources that can potentially accelerate charged particles up to GeV and TeV energies. These accelerated particles can produce Very High Energy (E>100 GeV) gamma-ray emission through different non-thermal processes such as inverse Compton scattering of ambient photon fields by accelerated electrons or pion decay after proton-proton collisions. Here we present highlight results of observations with the MAGIC telescopes on Galactic sources: millisecond pulsars, supernova remnants (SNRs), pulsar wind nebulae (PWNe), novae and binary systems. In particular, we present the promising PeVatron candidate SNR G106.3+2.7 containing an energetic PWN named Boomerang. Also, in the ongoing search for new source classes we looked for very-high-energy emission from the millisecond pulsar PSR J0218+4232 that has long been considered as one of the best candidates. Furthermore, we present the observations during an exceptionally bright X-ray outburst from the low mass X-ray binary MAXI J1820+070. Finally, we highlight the MAGIC results of the first nova detected at VHEs: RS Ophiuchi, a recurrent symbiotic nova located in the Milky Way. The detection with the MAGIC telescopes proves a hadronic origin of the the gamma-ray emission, and helps in understanding the contribution of novae to the cosmic-ray budget.

Gamma-ray Spectral Line emission search from Dark Matter Annihilation up to 100 TeV towards the Galactic Centre with MAGIC

Inada T., Kerszberg D., Hütten M., Rico J., Teshima M., Kohri K., Hiroshima N., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The detection of line-like TeV gamma-ray features configures as a smoking gun for the discovery of TeV-scale particle dark matter. We report the first search for dark matter spectral lines in the Galactic Centre region up to gamma-ray energies of 100 TeV with the MAGIC telescopes (La Palma, Canary Islands). The Galactic Centre region is expected to host the closest dark matter halo of considerable size and is therefore well suited for this kind of searches. Observations at large zenith angles improve sensitivity for gamma rays in the TeV regime due to the increased telescope collection area. We present the results obtained with more than 200 hours of large-zenith angle observations of the Galactic Centre region, which allow us to obtain competitive limits to the dark matter annihilation cross-section at high particle masses (< 5 × 10−28 cm3 s−1 at 1 TeV and < 1 × 10−25 cm3 s−1 at 100 TeV), improving the best current constraints above 20 TeV. In addition, we also study the impact of an inner cored dark matter halo on probing the annihilation cross-section. Finally, we use the derived limits to constrain super-symmetric wino models.

Galactic Center Studies with CTA-LST-1

Abe S., Ohtani Y., Strzys M., Teshima M., Vovk I., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Galactic Center region is known to host a wide variety of very-high-energy gamma-ray sources. In 2018 the prototype of the Large-Sized Telescope (LST-1) for CTA was inaugurated, and has been regularly observing the Galactic Center since 2021. To observe the Galactic Center in the southern sky, LST-1, located in the Northern hemisphere, requires an observation mode at a low telescope elevation. In this study, we assessed the performance of LST-1 at the large zenith angle, based both on simulations and observational data for the standard candle Crab Nebula. Analyzing LST-1 data from the Galactic Center observations, we obtained the spectral energy distributions of Sagittarius A* and G0.9+0.1, which were comparable with the results from the current imaging atmospheric Cherenkov telescopes, with a broad energy coverage owing to the large-zenith-angle observation and the low energy threshold of LST-1.

First Science Results from CTA LST-1 Telescope and status of LST-2-4

Mazin D., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D., Giesbrecht Paiva J., Giglietto N., Giordano F., Gliwny P.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The prototype Large-Sized Telescope (LST-1) of the Cherenkov Telescope Array (CTA) was inaugurated on La Palma, Canary Islands, in 2018. Since then, the telescope is in the commissioning phase and takes regular gamma-ray data on astrophysical sources while waiting for other CTA telescopes in La Palma to be constructed. Here we present the status of the commissioning, lessons learned, the telescope performance, and scientific highlights achieved in the last couple of years. The science results include the detection of active galactic nuclei flares, studies of pulsar wind nebulae and pulsars, the detection of a Nova, and searches for gamma-ray emission from gamma-ray bursts. We also present the status of the construction of the three further LST telescopes (LST-2-4) in La Palma and plans for their commissioning.

First results of pulsar observations with the LST-1

Mas-Aguilar Á., Brunelli G., Ceribella G., López-Moya M., López-Coto R., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

After the discovery of Crab, Vela, and Geminga pulsars at Very High Energies, the search for new pulsars at tens of GeV has been gaining huge importance. However, their steep spectra along with the sensitivity of the current generation of Imaging Atmospheric Cherenkov telescopes (IACTs) are limiting the capability to detect more pulsars. The LST-1 is the first prototype of the Large-Sized Telescope of the forthcoming CTA observatory with enhanced sensitivity at tens of GeV. The LST-1 started its commissioning phase in 2018, and since then it has observed the Crab pulsar regularly. Here, we show the first results of the analysis of the Crab and other pulsars taken with the LST-1. The two characteristic emission peaks of the Crab pulsar, P1, and P2, are detected with high significance showing a clear improvement in sensitivity over the previous generation of IACTs. The spectrum is reconstructed up to 450 GeV for P1 and up to 700 GeV for P2. The low energy threshold of LST-1 also allows us to measure the spectrum of the Crab pulsar in the overlapping region with the Fermi-LAT and cross-calibrate both instruments. The results obtained with the first pulsar observations with the LST-1 confirm the excellent potential of LST telescopes to study and discover new pulsars in the near future.

Expected exclusion limits to TeV dark matter from the Perseus Cluster with the Cherenkov Telescope Array

Adam R., Hernández-Cadena S., Hütten M., Pérez-Romero J., Sánchez-Conde M.A., Abe K., Abe S., Acharyya A., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F., Contreras J.L.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Clusters of galaxies are the largest gravitationally-bound structures in the Universe. They are composed of galaxies and gas (approximately 15% of the total mass) mostly dark matter (DM, accounts up to 85% of the total mass). If the DM is composed of Weakly Interacting Massive Particles (WIMPs), galaxy clusters represent one of the best targets to search for gamma-ray signals induced by the decay of WIMPs, with masses around the TeV scale. Due to its sensitivity and energy range of operation (from 20 GeV to 300 TeV), the Cherenkov Telescope Array (CTA) Observatory has a unique opportunity to test WIMPs with masses close to the unitarity limit. This will complement the searches for DM from other gamma-ray observatories as well as direct and collider experiments. The CTA Observatory is planning to search for gamma-ray emission, either its origin may be cosmic-ray (CR) or DM related, in the Perseus galaxy cluster during the first years of operation. In this poster, we will present the software created to perform the analysis using the ctools software and the corresponding results.

Evidence of hadronic origin of the gamma-ray emission from the nova RS Oph by the MAGIC telescopes

Green D.M., Ramazani V.F., Leone F., López-Coto R., López-Oramas A., Sitarek J., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fallah Ramazani V., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

RS Ophiuchi (RS Oph) is a symbiotic recurrent nova that shows eruptive events roughly every 15 years. On August 8th, 2021, RS Oph erupted with its latest outburst. This event was detected by a wide range of multi-wavelength (MWL) instruments from radio up to very-high-energy (VHE) gamma rays. The MAGIC telescopes followed up on optical and high-energy triggers and initiated an observation campaign from August 9th till September 1st. RS Oph is the first nova detected in the VHE gamma-ray energy range. We report on the detection of VHE gamma rays at a significant level of 13.2σ during the first 4 days of RS Oph with the MAGIC telescopes. We combine the VHE emission detected by MAGIC with optical and high energy observations and conclude RS Oph accelerated hadrons during its eruption. We will present the MWL modeling revealing this hadronic emission, and its further implications for Galactic cosmic-rays.

Evaluation of the effective mirror area of CTA Small-Sized Telescopes for camera design and Monte Carlo simulation

Okumura A., Ross D., Saturni F.G., Sironi G., White R.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The effective mirror area of an imaging atmospheric Cherenkov telescope is a crucial key parameter for trigger threshold determination and energy calibration. It is usually calculated by 3D ray-tracing simulation using a simplified telescope model, and the result is used in Monte Carlo simulations. However, simplified telescope and camera models are not adequate for the Schwarzschild–Couder configuration to be used in Small-Sized Telescopes (SSTs) of the Cherenkov Telescope Array. This is because the complex 3D structure of the secondary mirror, telescope masts, and camera body block a significant fraction of Cherenkov and night-sky photons. To evaluate the effective mirror area of an SST and to finalize its camera body design with minimal shadowing, a complex 3D model was built and simulated using the ROBAST ray-tracing library. A camera body size of 570 mm and a window size of 430 mm were selected for the final camera design based on the evaluation of shadowing by simulation. A non-axisymmetric effective area distribution was determined via the modeling of the complex telescope structure, while meeting the SST effective area requirement.

Development of a blue-mirror multilayer coating on light concentrators for future SiPM cameras

Okumura A., Haga J., Inoue C., Nishimoto K., Furuta K., Tajima H.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Silicon photomultipliers (SiPMs) have a few advantages over conventional photomultiplier tubes (PMTs) used in imaging atmospheric Cherenkov telescopes. The first notable characteristic is their higher photon detection efficiency (PDE) of up to about 60%, which is roughly 1.2–1.5 times better than that of PMTs in the 300–450 nm range, enabling us to lower the energy threshold of gamma-ray observations and increase the photon statistics. The second advantage is that SiPMs are chemically stable after exposure to long and bright illumination, while PMTs can cause gain and quantum efficiency degradation after the same exposure. Therefore, the use of SiPMs under bright or full moon conditions may extend the total observation time in the highest energy coverage region of individual telescopes. However, the SiPM PDE is too high in wavelengths longer than 500 nm; hence, the signal-to-noise ratio (S/N) of the Cherenkov signal over the night-sky background (NSB) is not necessarily superb. This is because the Cherenkov signal is dominant over the wavelength of 300–500 nm, while the NSB is brighter in the region of 550 nm or longer. To improve the S/N with minimal and cost-effective additional hardware, we have developed multilayer coating designs with only 8 layers and applied them to the specular surfaces of light concentrators. The layers were designed to reflect more photons in the 300–500 nm range but fewer in 550–800 nm. Using a prototype light concentrator fabricated with the novel multilayer design, we demonstrated that a SiPM array exhibits ∼50% better photon collection efficiency at 403 nm than that obtained with PMTs, agreeing with the result of a ray-tracing simulation. The efficiency measured at 830 nm was also successfully reduced by 30–50%.

Detection of the 2021 Outburst of RS Ophiuchi with the LST-1

Kobayashi Y., Aguasca-Cabot A., Bernardos Martín M.I., Green D., López-Coto R., Abe K., Abe S., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Novae are luminous explosions in close binaries which host a white dwarf and a companion donor star. They are triggered by a thermonuclear runaway when the white dwarf accretes a critical amount of matter from the secondary. Though novae are established as high-energy gamma-ray emitters through observations by the Fermi Large Area Telescope (LAT), the origin of the gamma-ray emission, whether it is hadronic or leptonic, had been under intense debate until very recently. RS Ophiuchi (RS Oph) is a well-known recurrent symbiotic nova with a recurrence time scale of 15 years. The most recent outburst of RS Oph in 2021 brought the first detection of very-high-energy (VHE) gamma rays from a nova ever. The first Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array observed this historic event along with H.E.S.S. and MAGIC. The LST-1 observations in the first days after the burst onset show a clear VHE gamma-ray signal from RS Oph. The low energy threshold of LST-1 allows us to reconstruct the RS Oph gamma-ray spectrum down to ∼30 GeV, providing the best connection of the VHE gamma-ray data to the Fermi LAT energy range. The results from the analysis of the LST-1 observations are consistent with those obtained with H.E.S.S. and MAGIC, and also support a hadronic origin for the observed gamma-ray fluxes. In this contribution, we will present the analysis results of the LST-1 observations of the 2021 outburst of RS Oph.

Detecting and characterizing pulsar halos with the Cherenkov Telescope Array Observatory

Eckner C., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F., Contreras J.L., Cossou C., Costa A., Costantini H., Cristofari P.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The recently identified source class of pulsar halos may be populated and bright enough at TeV energies to constitute a large fraction of the sources that will be observed with the Cherenkov Telescope Array (CTA), especially in the context of the planned Galactic Plane Survey (GPS). In this study, we examine the prospects offered by CTA for the detection and characterization of such objects. CTA will cover energies from 20 GeV to 300 TeV, bridging the ranges already probed with the Fermi Large Area Telescope and High Altitude Water Cherenkov Observatory, and will also have a better angular resolution than the latter instruments, thus providing a complementary look at the phenomenon. From simple models for individual pulsar halos and their population in the Milky Way, we examine under which conditions such sources can be detected and studied from the GPS observations. In the framework of a full spatial-spectral likelihood analysis, using the most recent estimates for the instrument response function and prototypes for the science tools, we derive the spectral and morphological sensitivity of the CTA GPS to the specific intensity distribution of pulsar halos. From these, we quantify the physical parameters for which pulsar halos can be detected, identified, and characterized, and what fraction of the Galactic population could be accessible. We also discuss the effect of interstellar emission and data analysis systematics on these prospects.

Defining the data legacy of the MAGIC telescopes: adopting a standardised data format and open-source analysis tools

Nigro C., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K., Jiménez Martínez I., Jormanainen J.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Very-high-energy (VHE, E > 100 GeV) gamma-ray telescopes have traditionally conducted science with proprietary data and software. After two decades of operations, they have accumulated thousands of hours of observations whose full scientific exploitation cannot be accomplished by the restricted group of scientists operating these instruments. The advent of a new generation of open gamma-ray observatories and, at the same time, the forthcoming end of their scientific operations, call for the realisation of public archives of their observations. With the objective to facilitate the exchange and dissemination of data from current- and next-generation gamma-ray instruments, the "Data formats for gamma-ray astronomy" (GADF) initiative was formed to provide an open and standardised format for gamma-ray astronomical data. In this contribution, we present the effort to produce data of the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes in this standardised format. A total of 150 hours of observations of different sources were converted to the GADF format and then validated by analysing them with the open-source software Gammapy and comparing the results obtained against those produced with the MAGIC proprietary software, MARS. The effort to standardise and validate the MAGIC data in an open and shared format constitute the first fundamental milestone towards the realisation of its public data legacy.

Dark matter searches in dwarf spheroidal galaxies with the Cherenkov Telescope Array

Saturni F.G., Doro M., Morselli A., Rodríguez-Fernández G., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F., Contreras J.L., Cossou C.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Dark matter (DM) is one of the major components in the Universe. However, at present its existence is still only inferred through indirect astronomical observations. DM particles can annihilate or decay, producing final-state Standard Model pairs that subsequently annihilate into high-energy γrays. The dwarf spheroidal galaxies (dSphs) in the Milky Way DM halo have long been considered optimal targets to search for annihilating DM signatures in GeV-to-TeV γ-ray spectra due to their high DM densities (hence high astrophysical factors), as well as the expected absence of intrinsic γ-ray emission of astrophysical origin. For such targets, it is important to compute the amount of DM in their halos in a consistent way to optimize the γ-ray data analysis. Such estimates directly affect the observability of DM signals in dSphs, as well as the DM constraints that can be derived in case of null detection. In this contribution, we present the results on the sensitivity of the Cherenkov Telescope Array (CTA) for DM annihilation and decay searches using planned observations of the Milky Way dSphs. We select the most promising targets among all presently known dwarf satellites, providing new determinations of their expected DM signal. This study shows an improvement of approximately an order of magnitude in sensitivity compared to current searches in similar targets. We also discuss the results in terms of cuspy and cored DM models, and investigate the sensitivity obtained by the combination of observations from different dSphs. Finally, we explore the optimal strategies for CTA observations of dSphs.

Ctapipe - Prototype Open Event Reconstruction Pipeline for the Cherenkov Telescope Array

Linhoff M., Beiske L., Biederbeck N., Fröse S., Kosack K., Nickel L., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., de Almeida U.B., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array Observatory (CTAO) is the next-generation ground-based gamma-ray observatory currently under construction. It will improve over the current generation of imaging atmospheric Cherenkov telescopes (IACTs) by a factor of five to ten in sensitivity and it will be able to observe the whole sky from a combination of two sites: a northern site in La Palma, Spain, and a southern one in Paranal, Chile. CTAO will also be the first open ground-based gamma-ray observatory. Accordingly, the CTAO data processing pipeline is developed as open-source software and ctapipe will be a core package therein. The event reconstruction pipeline accepts raw data of the telescopes and processes it to produce suitable input for the higher-level science tools. Its primary tasks include reconstructing the physical properties of each recorded air shower and providing the corresponding instrument response functions. ctapipe is a python framework providing algorithms and command-line tools to facilitate raw data calibration, image extraction, image parametrization and event reconstruction. Its current main focus is the analysis of simulated data but it has also been successfully applied for the analysis of data obtained with the CTA prototype telescopes, and first science results have now been obtained by the LST-1 collaboration using ctapipe. A plugin system also allows the processing of nonCTA data. Recent updates, including event reconstruction using machine learning and a new plugin system as well as the roadmap towards a 1.0 release will be presented.

Constraints on axion-like particles with the Perseus Galaxy Cluster with MAGIC

D’Amico G., Batković I., Doro M., Manganaro M., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K., Jiménez Martínez I., Jormanainen J.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Axion-like particles (ALPs) are pseudo-Nambu-Goldston bosons that appear in theories beyond the standard model and are capable of converting to photons in the presence of magnetic fields. Such interaction can have an observable effect on the gamma-ray spectrum of astrophysical targets. We have examined about 40 hours of observations made with the ground-based MAGIC Cherenkov telescopes in the direction of the Perseus Galaxy Cluster. The sources of VHE gamma rays present in the cluster and object of the study are the radiogalaxy NGC1275 and the HBL object IC310. These sources are bright in gamma rays and embedded in the cluster’s high magnetic field, making them very good targets for this kind of study. Having not found statistical evidence for ALPs, we exclude ALPs models with masses in the sub-eV range in line with previous results. Last, we address the potential for gamma-ray-based instruments, both current and future, to identify ALP signals using this analysis technique, finding that the search for wiggles in TeV gamma-ray spectra is very unlikely to be sensitive enough for observations with IACTs.

Chasing Gravitational Waves with the Cherenkov Telescope Array Open Access

Green J.G., Carosi A., Nava L., Patricellix B., Schüssler F., Seglar-Arroyo M., Stamerra A., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The detection of gravitational waves (GWs) from a binary neutron star (BNS) merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this GW event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a GW signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. Achieving such a feat will require a comprehensive real-time strategy capable of coordinating searches over potentially very large regions of the sky. This work will evaluate and provide estimations on the number of GW-CTA events determined from simulated BNS systems and short GRBs, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.

DOI： 10.22323/1.444.1534

Characterization of SiPM and development of test bench modules for the next-generation cameras for Large-Sized Telescopes for Cherenkov Telescope Array

Saito T., Hashiyama K., Iwasaki H., Kubo H., Mizote M., Okumura A., Tajima H., Yamamoto T.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The recent improvements in the performance of the silicon photomultipliers (SiPMs) made them attractive options as photo sensors of imaging atmospheric Cherenkov telescopes (IACTs). In fact, they are already adopted in some IACTs such as FACT and the Small-Sized Telescopes of the Cherenkov Telescope Array (CTA). However, the application to the Large-Sized Telescopes (LSTs) of CTA requires additional studies. As the pixel size of LSTs is larger than the nominal size of SiPMs, the signal from multiple sensors must be summed up. Also, the high detection efficiency of the night sky background (NSB) photons may degrade the telescope performance. To overcome this, the pulse width must be as small as 3 ns and the detection efficiency for NSB photons must be suppressed as much as possible. Heat generation and gain stabilization are also issues. We studied different types of SiPMs from Hamamatsu photonics and characterized them for the LST application, addressing the previous points. Also, to prove the SiPM performance in LST, we are developing a SiPM module which can be installed in the exisiting LST camera. Here we present the results of this evaluation and the status of the test bench module development.

Bright blazar flares with CTA

Cerruti M., Finke J., Grolleron G., Lenain J.P., Hovatta T., Joshi M., Lindfors E., Morris P., Petropoulou M., Romano P., Vercelloneh S., Zacharias M., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., de Almeida U.B., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Chaty S., Chen A.W., Chernyakova M.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The TeV extragalactic sky is dominated by blazars, radio-loud active galactic nuclei with a relativistic jet pointing towards the Earth. Blazars show variability that can be quite exceptional both in terms of flux (orders of magnitude of brightening) and time (down to the minute timescale). This bright flaring activity contains key information on the physics of particle acceleration and photon production in the emitting region, as well as the structure and physical properties of the jet itself. The TeV band is accessed from the ground by Cherenkov telescopes that image the pair cascade triggered by the interaction of the gamma ray with the Earth's atmosphere. The Cherenkov Telescope Array (CTA) represents the upcoming generation of imaging atmospheric Cherenkov telescopes, with a significantly higher sensitivity and larger energy coverage with respect to current instruments. It will thus provide us with unprecedented statistics on blazar light-curves and spectra. In this contribution we present the results from realistic simulations of CTA observations of bright blazar flares, taking as input state-of-the-art numerical simulations of blazar emission models and including all relevant observational constraints.

Interpolation of Instrument Response Functions for the Cherenkov Telescope Array in the Context of pyirf

Dominik R.M., Linhoff M., Sitarek J., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., de Almeida U.B., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F., Contreras J.L., Cossou C., Costa A.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next generation ground-based very-high-energy gamma-ray observatory, constituted by tens of Imaging Atmospheric Cherenkov Telescopes at two sites once its construction and commissioning are finished. Like its predecessors, CTA relies on Instrument Response Functions (IRFs) to relate the observed and reconstructed properties to the true ones of the primary gamma-ray photons. IRFs are needed for the proper reconstruction of spectral and spatial information of the observed sources and are thus among the data products issued to the observatory users. They are derived from Monte Carlo simulations, depend on observation conditions like the telescope pointing direction or the atmospheric transparency and can evolve with time as hardware ages or is replaced. Producing a complete set of IRFs from simulations for every observation taken is a time-consuming task and not feasible when releasing data products on short timescales. Consequently, interpolation techniques on simulated IRFs are investigated to quickly estimate IRFs for specific observation conditions. However, as some of the IRFs constituents are given as probability distributions, specialized methods are needed. This contribution summarizes and compares the feasibility of multiple approaches to interpolate IRF components in the context of the pyirf python software package and IRFs simulated for the LargeSized Telescope prototype (LST-1). We will also give an overview of the current functionalities implemented in pyirf.

Update on the performance of the MAGIC Intensity Interferometer

Martínez I.J., Acciari V.A., Cifuentes A., Colombo E., Cortina J., Delgado C., Díaz C., Fiori M., Fink D., Guberman D., Hassan T., Lyard E., Mariotti M., Martínez G., Mirzoyan R., Naletto G., Njoh Ekoume T., Polo M., Produit N., Rodríguez-Vázquez J.J., Saha P., Schweizer T., Walter R., Wunderlich C.W., Zampieri L., Abe H., Abe S., Abhir J., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Be-Cerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cikota S., Contreras J.L., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

In recent years, the MAGIC telescopes have been equipped with a setup that allows its Imaging Atmospheric Cherenkov Telescopes (IACTs) to function as an Intensity Interferometer. The deadtime-free setup includes a 4-channel GPU-based real-time correlator together with optical filters in the 350-450 nm wavelength range and specialized Active Mirror Control (AMC) configurations. This implementation allows MAGIC to perform measurements of the spatial coherence (visibility) of the intensity fluctuations of an object’s starlight over several separations (baselines) and construct a model of said object. The accessible baseline range for MAGIC is 40-90 m which translates into an angular resolution of 0.5-1 mas. Additionally, thanks to the AMC it can access even smaller baselines, of less than 17 m (which is the diameter of each of both dishes) to measure objects of greater angular size (>1 mas) and even measure the zero-baseline correlation, which is key to calibrate the system. We present the latest measurements that allow us to understand the performance and systematics of our setup and validate our analysis.

The Real Time Analysis framework of the Cherenkov Telescope Array’s Large-Sized Telescope

Caroff S., Aubert P., Garcia E., Maurin G., Pollet V., Vuillaume T., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Large-Sized Telescopes (LSTs) of the Cherenkov Telescope Array Observatory (CTAO) will play a crucial role in the study of transient gamma-ray sources, such as gamma-ray bursts and flaring active galactic nuclei. The low energy threshold of LSTs makes them particularly well suited for the detection of these phenomena. The ability to detect and analyze gamma-ray transients in real-time is essential for quickly identifying and studying these rare and fleeting events. In this conference, we will present recent advances in the real-time analysis of data from the LST-1, the first prototype of LST located in the Canary island of La Palma. We will discuss in particular the development of new algorithms for event reconstruction and background rejection. These advances will enable rapid identification and follow-up observation of transient gamma-ray sources, making the LST-1 a powerful tool for the study of the dynamic universe. The implementation of this framework in the future Array Control and Data Acquisition System (ACADA) of CTAO will be discussed as well, based on the experience with LST.

The rapporteur report on the diversity session at the ICRC2023 Open Access

Takahashi S., Ishihara A., Okumura A., Itow Y.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Diversity Session at ICRC2023 marked a significant step towards enhancing inclusivity within the astroparticle community. This report not only documents the lively discussions of the session but also highlights a cornerstone of our efforts: the outcomes of the pre-conference diversity survey. Professor Hiromi Yokoyama’s thought-provoking presentation illuminated a pivotal aspect: the factors affecting the attrition of female students, particularly in the field of physics.

DOI： 10.22323/1.444.0038

The next generation cameras for the Large-Sized Telescopes of the Cherenkov Telescope Array Observatory

Heller M., Altet J., Aragones X., Barrio J.A., Bellato M., Bernasconi E., Biland A., Blanch O., Burmistrov L., Charbon E., Dalchenko M., Di Pierro F., Giangrande L., Gascon D., Gòmez S., Hoffmann D., Martinez G., Mariotti M., Matteo D., Montaruli T., Okumura A., Aguilera A.P., Manera R., Rando R., Saito T., Sanuy A., Tejedor L.A., Uzun Y.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The latest generation of silicon photomultipliers (SiPM) offers twice as much sensitivity to Cherenkov light observed at ground level when compared to photomultipliers. Their use for imaging atmospheric Cherenkov telescopes is increasing, from the FACT telescope, the pioneer, to the small-sized telescopes of the Cherenkov Telescope Array (CTA) or the LHAASO WFCTA camera. The robustness of the SiPMs represents a unique opportunity to ensure long-term operation with low maintenance. In this work, we present the latest developments and performance of a SiPM camera aiming at upgrading the large-sized telescopes (LST) cameras of CTA. The SiPM camera, equipped with 0.05 deg pixels, provides images of improved resolution for better feature extraction. The increase in the number of pixels has driven the development of low-power front-end electronics whose design is presented in this work. We also present the fully digital readout architecture of the proposed camera, which will enable the implementation of novel triggering algorithms based on artificial intelligence.

The Cosmic-ray Electron and Positron Spectrum Measured with MAGIC

Chai Y., Ishio K., Kerszberg D., Mangano S., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Cosmic-ray electrons and positrons (CREs) of TeV energies suffer severe energy loss during propagation due to inverse Compton scattering and synchrotron radiation process, they are therefore very useful to constrain the local cosmic-ray sources in the Galaxy. The ability to measure CREs by ground-based imaging atmospheric Cherenkov telescopes (IACTs) has been demonstrated in the past. In this proceeding, we will present two methods – a template fit method and a tight cut method based on a two-steps-trained Random Forest (RF) – optimized for the detection and study of CREs and will report on the measurement of the CREs energy spectrum from 300 GeV to 6 TeV with the MAGIC telescopes.

Study on the gain and photon detection efficiency drops of silicon photomultipliers under bright background conditions

Okumura A., Wakazono K., Furuta K., Tajima H.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The use of silicon photomultipliers (SiPMs) in imaging atmospheric Cherenkov telescopes is expected to extend the observation times of very-high-energy gamma-ray sources, particularly within the highest energy domain of 50–300 TeV, where the Cherenkov signal from celestial gamma rays is adequate even under bright moonlight background conditions. Unlike conventional photomultiplier tubes, SiPMs do not exhibit quantum efficiency or gain degradation, which can be observed after long exposures to bright illumination. However, under bright conditions, the photon detection efficiency of a SiPM can be undergo temporary degradation because a fraction of its avalanche photodiode cells can saturate owing to photons from the night-sky background (NSB). In addition, the large current generated by the high NSB rate can increase the temperature of the silicon substrate, resulting in shifts in the SiPM breakdown voltages and consequent gain changes. Moreover, this large current changes the effective bias voltage because it causes a voltage drop across the protection resistor of 100–1000 Ω. Hence, these three factors, namely the avalanche photodiode (APD) saturation, Si temperature, and voltage drop must be carefully compensated for and/or considered in the energy calibration of Cherenkov telescopes with SiPM cameras. In this study, we measured the signal output charge of a SiPM and its variation as a function of different NSB-like background conditions up to 1 GHz/pixel. The results verify that the product of the SiPM gain and photon detection efficiency is well characterized by these three factors.

Sensitivity of the Cherenkov Telescope Array to the gamma-ray emission from neutrino sources detected by IceCube

Sergijenko O., Brown A.M., Fiorillo D., de León A.R., Satalecka K., Tung C.F., Taboada I., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Gamma-ray observations of the astrophysical neutrino sources are fundamentally important for understanding the underlying neutrino production mechanism. We investigate the Cherenkov Telescope Array (CTA) ability to detect the very-high-energy (VHE) gamma-ray counterparts to the neutrino-emitting Active Galaxies. The CTA performance under different configurations and array layouts is computed based on the neutrino and gamma-ray simulations of steady and transient types of sources, assuming that the neutrino events are detected with the IceCube neutrino telescope. The CTA detection probability is calculated for both CTA sites taking into account the visibility constraints. We find that, under optimal observing conditions, CTA could observe the VHE gamma-ray emission from at least 3 neutrino events per year.

Pybkgmodel - a background modelling toolbox for the CTA

Strzys M.C., Abe S., de Bony de Lavergne M., Hütten M., Mender S., Vovk I., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., de Almeida U.B., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Despite the advancement in background rejection techniques, observation of the very-high-energy gamma-ray sky by imaging atmospheric Cherenkov telescopes (IACTs) are subject to an irreducible background from gamma-like hadron- or electron-induced air showers. The determination of this residual background is crucial for accurate spectral and spatial measurements. The Cherenkov Telescope Array (CTA) will become the next generation of IACTs. To unveil its full potential, the improved reconstruction performance of CTA needs to be coupled with a reliable background estimate across the entire field of view. This may become especially important in the case of the planned surveys of large areas of the sky. In this contribution we will present pybkgmodel, an open-source python software package developed for CTA. It aims at providing in a consistent way the various background modelling methods, based on the experience from current IACTs such as H.E.S.S, MAGIC, and VERITAS. It is designed as a toolbox allowing a user to easily choose the optimal reconstruction approach for various target regions or a combination of several algorithms. We will introduce the design of the package as well as demonstrate its functionality using data for the CTA Large-Sized Telescope prototype (LST-1).

Potential of the Cherenkov Telescope Array for studying the young nearby supernova remnants

Prokhorov D.A., Lee S.H., Nagataki S., Vink J., Ellison D.C., Ferrand G., Patnaude D.J., Roepke F.K., Seitenzahl I.R., Slane P.O., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Modern imaging atmospheric Cherenkov telescopes have extensively observed young nearby supernova remnants (SNRs), with ages of about 1000 years or less, in the very-high-energy (VHE) gamma-ray band. These efforts resulted in the detection of VHE emission from three young SNRs – Cassiopeia A, Tycho, and SN 1006 – and provided significant evidence for emission from the more distant Kepler’s SNR. However, many questions on the production of VHE gamma rays in these remnants remain unanswered. Using detailed physical models for Tycho’s SNR based on the CR-hydro-NEI code and physically motivated models for the other young nearby remnants, we simulated observations with the Cherenkov Telescope Array (CTA) of these gamma-ray sources. We highlight properties of these remnants accessible for investigation with future CTA observations and discuss which questions are expected to be answered.

Performance update of an event-type based analysis for the Cherenkov Telescope Array

Bernete J., Gueta O., Hassan T., Linhoff M., Maier G., Sinha A., Abe K., Abe S., Acharyya A., Adam R., Aguasca-Cabot A., Agudo I., Alfaro J., Alvarez-Crespo N., Alves Batista R., Amans J.P., Amato E., Ambrosino F., Angüner E.O., Antonelli L.A., Aramo C., Arcaro C., Arrabito L., Asano K., Aschersleben J., Ashkar H., Augusto Stuani L., Baack D., Backes M., Balazs C., Balbo M., Baquero Larriva A., Barbosa Martins V., de Almeida U.B., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Batzofin R., Baxter J., Beck G., Becker Tjus J., Beiske L., Belardinelli D., Benbow W., Bernardini E., Bernete Medrano J., Bernlöhr K., Berti A., Beshley V., Bhattacharjee P., Bhattacharyya S., Bi B., Biederbeck N., Biland A., Bissaldi E., Blanch O., Blazek J., Boisson C., Bolmont J., Bonnoli G., Bordas P., Bosnjak Z., Bradascio F., Braiding C., Bronzini E., Brose R., Brown A.M., Brun F., Brunelli G., Bulgarelli A., Burelli I., Burmistrov L., Burton M., Bylund T., Calisse P.G., Campoy-Ordaz A., Cantlay B.K., Capalbi M., Caproni A., Capuzzo-Dolcetta R., Carlile C., Caroff S., Carosi A., Carosi R., Carrasco M.S., Cascone E., Cassol F., Castrejon N., Catalani F., Cerasole D., Cerruti M., Chaty S., Chen A.W., Chernyakova M., Chiavassa A., Chudoba J., Coimbra Araujo C.H., Conforti V., Conte F.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next-generation observatory in the field of very-high-energy (20 GeV to 300 TeV) gamma-ray astroparticle physics. The traditional approach to data analysis in this field is to apply quality cuts, optimized using Monte Carlo simulations, on the data acquired to maximize sensitivity. Subsequent steps of the analysis typically use the surviving events to calculate one set of instrument response functions (IRFs) to physically interpret the results. However, an alternative approach is the use of event types, as implemented in experiments such as the Fermi-LAT. This approach divides events into sub-samples based on their reconstruction quality, and a set of IRFs is calculated for each sub-sample. The sub-samples are then combined in a joint analysis, treating them as independent observations. In previous works we demonstrated that event types, classified using Machine Learning methods according to their expected angular reconstruction quality, have the potential to significantly improve the CTA angular and energy resolution of a point-like source analysis. Now, we validated the production of event-type wise full-enclosure IRFs, ready to be used with science tools (such as Gammapy and ctools). We will report on the impact of using such an event-type classification on CTA high-level performance, compared to the traditional procedure.

Performance of the Large-Sized Telescope prototype of the Cherenkov Telescope Array

Morcuende D., López-Coto R., Moralejo A., Nozaki S., Vuillaume T., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The next-generation ground-based gamma-ray Cherenkov Telescope Array Observatory (CTAO) will consist of imaging atmospheric Cherenkov telescopes (IACTs) of three different sizes distributed in two sites. The Large-Sized Telescopes will cover the low-energy end of the CTA energy range, starting at about 20 GeV. After its first years of operation at the CTA northern site, the Large-Sized Telescope prototype (LST-1) is in the final stage of its commissioning phase, having collected a significant amount of scientific data to date. In this contribution, we present the physics performance of the telescope using low-zenith Crab Nebula observations and Monte Carlo simulations fine-tuned accordingly. We show performance figures of merit such as the energy threshold, effective area, energy and angular resolution, and sensitivity based on the standard Hillas-parameters approach and following the source-independent and dependent analysis methods. The analysis threshold is estimated at 30 GeV. The energy resolution is around 30%, and the angular resolution is 0.3 degrees at 100 GeV. The best integral sensitivity of LST-1 is about 1.1% of the Crab Nebula flux above 250 GeV for 50 hours of observations. We also show the spectral energy distribution and light curve from Crab Nebula observations, which agree with results from other IACTs and link smoothly with Fermi-LAT when considering statistical and systematic uncertainties near the energy threshold.

Performance of joint gamma-ray observations with MAGIC and LST-1 telescopes

Di Pierro F., Berti A., de Menezes R., Jobst E., Ohtani Y., Sitarek J., Suda Y., Visentin E., Abe H., Abe K., Abe S., Abhir J., Acciari V.A., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Aniello T., Ansoldi S., Antonelli L.A., Aramo C., Arbet-Engels A., Cornelia A., Artero M., Asano K., Aubert P., Baack D., Babić A., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M.I., Bernete Medrano J., Besenrieder J., Bhattacharjee P., Biederbeck N., Bigongiari C., Biland A., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bošnjak , Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Busetto G., Campoy-Ordaz A., Cardillo M., Caroff S., Carosi A., Carosi R., Carrasco M.S., Carretero-Castrillo M., Cassol F., Castro-Tirado A.J., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chilingarian A., Chytka L., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Costantini H., Covino S., D’Amico G., Dalchenko M., D’Elia V., Da Vela P., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., Del Peral L., Deleglise G., Delfino M., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Del Popolo A., Depaoli D., Di Piano A.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The prototype Large-Sized Telescope (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) is in commissioning phase at the Observatorio del Roque de Los Muchachos at 2200 m a.s.l. in La Palma (Canary Islands, Spain). LST-1 is a 23-m diameter telescope and is the first of four that will compose the LST part of the CTAO Northern array. The LST subarray is optimized to provide the best sensitivity for gamma rays in the 20 GeV - 200 GeV energy range. The MAGIC telescopes, which are located approximately 100 m from the LST-1, is operating as a two 17-m telescope stereoscopic system for more than 14 years. LST-1 and MAGIC routinely perform joint observations of gamma-ray sources to exploit the potential of the three-telescope system. This contribution describes the analysis pipeline and evaluates the performance of the system using Monte Carlo simulations and data on the Crab Nebula. The sensitivity achieved during joint observations with MAGIC and LST-1 is about 30% higher than that of MAGIC alone.

Observation of Active Galactic Nuclei with the Large-Sized Telescope prototype of the Cherenkov Telescope Array

Takeishi R., Álvarez Crespo N., Arbet-Engels A., Baquero Larriva A., Baxter J., Biederbeck N., Caroff S., Di Marco G., Fallah Ramazani V., Green D., Heckmann L., Láinez M., Nickel L., Nievas Rosillo M., Pons E., Priyadarshi C., Sanchez D.A., Vázquez Acosta M., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Antonelli L.A., Aramo C., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory. It will consist of three different sizes of telescopes, with a collective improvement of about an order of magnitude in sensitivity, compared with the current generation gamma-ray telescopes. LargeSized Telescopes (LSTs) will be the most sensitive at energies from tens of GeV up to a few TeVs, and will be the best suited to observe gamma-ray sources such as Active Galactic Nuclei (AGN). The first Large-Sized Telescope prototype (LST-1), inaugurated in 2018 and currently in commissioning phase, has accumulated more than one thousand hours of data to date. From 2020 to 2022, we have detected various gamma-ray sources, and prominent among them are several well-known AGN, like Mrk 421, Mrk 501, 1ES 1959+650, 1ES 0647+250, PG 1553+113, etc. We report on light curves and energy spectra reconstructed out of these observations down to energies of tens of GeV, which is very close to the energy threshold of LST-1.

New constraints on Lorentz invariance violation using the extraordinary flare of Mrk 421 in 2014

D’Amico G., Strišković J., Terzić T., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

An extraordinary flare from blazar Mrk 421 was recorded on the night of April 24, 2014, by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes at very high energy (VHE) from 100 GeV up to 10 TeV. Several quantum-gravity models indicate that the photon group velocity in vacuum may be energy dependent, known as in-vacuum dispersion. Violation of Lorentz Invariance (LIV) of this kind can lead to an observable effect on the time of flight of VHE photons from cosmic origin. Observations of fast and distant phenomena, such as the flare from Mrk 421, are excellent testing grounds for this hypothesis. Using an innovative binned likelihood analysis, for the first time from this source we were able to search for arrival-time delays scaling linearly or quadratically with the energy of the photon. The non-detection of energy-dependent time delays led us to set constraints on the parameter space of quantum-gravity predictions.

Multiwavelength study of GRB 201216C using the sub-TeV emission detected by MAGIC

Fukami S., Berti A., Loporchio S., Nava L., Suda Y., Noda K., Asano K., Bošnjak Ž., Longo F., Jordana-Mitjans N., Melandri A., Mundell C., Shrestha M., Steele I., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Recently, several gamma-ray bursts (GRBs) have been detected in the very-high-energy (VHE) gamma-ray energy range by ground-based gamma-ray experiments such as MAGIC, H.E.S.S., and LHASSO. For some GRBs, the VHE emission is consistent with synchrotron self-Compton (SSC) emission from high-energy electrons accelerated in the forward shock of the relativistic jet. However, more statistics are needed to further constrain the emission models. GRB 201216C is a long bright GRB detected in a broad energy range from radio to VHE. The redshift is estimated to be 1.1, making the GRB the most distant source detected in the VHE energy range. MAGIC started the observation 56 seconds after the GRB was triggered by the Swift-BAT telescope. We performed a detailed analysis and detected the signal with about 6 sigma in the first 20 minutes. MAGIC continued the observation for 2.2 hours on the same night and 4 hours on the next night. No signal was detected later than 40 minutes after the GRB trigger. We have performed modelling of the multi-wavelength emission using the MAGIC data. We analysed simultaneous optical data from Liverpool Telescope with MAGIC and included the results in the modelling. The sub-TeV emission is consistent with the single-zone SSC model in the forward shock. In this presentation, we show the final results of the MAGIC data analysis of GRB 201216C and discuss the emission mechanism of the multi-wavelength data.

Multiwavelength characterization of two flaring blazars: insight into the emission region of intermediate-synchrotron-peaked BL Lacs

Loporchio S., Bonnoli G., Cerasole D., Di Venere L., Dominis Prester D., Giordano F., Lindfors E., Manganaro M., Pavletić L., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Be-Cerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., GiesbrechtPaiva J.G., Giglietto N., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The blazars B2 1811+31 and GB6 J1058+2817 were found to be in flaring state during 2020 and 2021, respectively. The high states of the sources were registered by the Fermi-LAT at energies below 100 GeV, triggering observations at higher energies with the MAGIC telescopes, in the UV/X rays with the Swift satellite and with ground-based radio and optical telescopes. The observations in the very-high-energy (VHE, 100 GeV < E < 100 TeV) gamma-ray band led to the first detection of both sources in this energy range. A long-term gamma-ray lightcurve was derived using Fermi-LAT data, identifying the time intervals in which the two sources persisted in a quiet state. Archival data collected in the radio to X-ray wavelengths showed that the two sources exhibited intermediate-synchrotron-peaked BL Lac behaviors in their low states, rather rare sources in the TeV sky. The high state of the two sources was deeply investigated thanks to the coverage provided by multi-wavelength (MWL) observational campaigns. In this contribution, we present the results of the gamma-ray observations which are included in a MWL observational campaign organized on these sources during their high-states. We discuss the flare spectral properties and temporal variability. In the high-energy gamma band, sub-daily-scale variability and strong spectral hardening give evidence for compact emission regions responsible for the radiative output at high energies during the flare.

Multi-wavelength analysis of the galactic PeVatron candidate LHAASO J2108+5157

Pirola G., Juryšek J., Balbo M., Eckert D., Tramacere A., Walter R., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Asano K., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Emery G., Escudero J., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

LHAASO J2108+5157 is a recently discovered source, detected in the Ultra-High-Energy band by the LHAASO collaboration. Two molecular clouds were identified in the direction coincident with LHAASO J2108+5157 and, from the spectra reported by LHAASO, there is no sign of an energy cutoff up to 200 TeV. This source makes a promising galactic PeVatron candidate. In 2021, the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array (CTA) Observatory, collected about 50 hours of quality-selected data on LHAASO J2108+5157. Through these observations, we managed to compute stringent upper limits on the source emission in the multi-TeV band. Together with the analysis of XMM-Newton data and 12 years of Fermi-LAT data, we performed a multi-wavelength study of the source, investigating different possible scenarios of particle acceleration. In this contribution, we will present the results of the analysis, as well as the multi-wavelength modeling, and consequent interpretation of different possible scenarios of emission.

MAGIC Upper Limits on the VHE emission from Flat Spectrum Radio Quasars

Mondal H.A., Gliwny P., Principe G., Longo F., Żywucka-Hejzner N., Lindfors E., Majumdar P., Sitarek J., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Blazars are a class of active galactic nuclei (AGN) where the relativistic jet is pointed towards the observer. They are powerful sources of non-thermal radiation from radio to very high energy (VHE, E>100 GeV) gamma-rays. Flat Spectrum Radio Quasars (FSRQs) are a subclass of blazars where there are absorption or emission lines present in the optical spectra. The observed properties of FSRQs are strongly affected by the magnetic field in the accretion disk which changes the UV emission of Broad Line Region (BLR) and infra-red emission from the Dusty Torus. While many (774 as reported in 4FGL-DR2 catalogue [1]) FSRQs have been detected at high energies (HE; E>100 MeV), only a few (9 as of now) could be detected at VHE. In this contribution, we present observations of nine FSRQs performed by Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC)telescopes between 2008 and 2020 with a total observation time of 174 hours. We also include a few observations from the Fermi-LAT, Swift-UVOT, Swift-XRT and optical observations from Kungliga Vetenskapsakademien (KVA) for two sources CTA 102 and B2 2234+28. We also modelled the broad band emission of the sources to look for signatures of absorption in the BLR region and hence to put constraints on the location of the emission region.

MAGIC observation of BL Lacertae flaring period in 2020

Imazawa R., Strišković J., Jormanainen J., Truzzi S., Lindfors E., Dominis Prester D., Bonnoli G., Fukazawa Y., Suda Y., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

BL Lacertae (BL Lac) is one of the low-frequency peaked BL Lac object (LBL). Since August 2020, BL Lac has shown a historically high activity in HE (high-energy, 0.1 GeV < E < 100 GeV) gamma-ray and optical bands. The MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes performed joint observations during this flaring period with instruments operating in gamma-ray, X-ray, optical, and radio bands from August to October 2020. In the VHE (very-high-energy, E > 100 GeV) gamma-ray range, BL Lac was detected in several nights during an especially bright flare simultaneous with a HE flare. In the long-term light curves, X-ray and HE gamma-ray flux overall show correlation, but sometimes only HE gamma-ray was bright. These multi-wavelength (MWL) correlations may relate to the emission mechanisms and the origin of the observed flaring activity. In this contribution we will present some of the preliminary results on the MWL campaign of BL Lac in September 2020, with a focus on the X-ray and gamma-ray activity, based on the data collected by Swift-XRT, MAGIC and Fermi-LAT telescopes.

LST-1 observations of an enormous flare of BL Lacertae in 2021

Nozaki S., Asano K., Escudero J., Emery G., Priyadarshi C., Abe K., Abe S., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Antonelli L.A., Aramo C., Arbet-Engels A., Arcaro C., Artero M., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Bhattacharjee P., Biederbeck N., Bigongiari C., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Cardillo M., Caroff S., Carosi A., Carrasco M.S., Cassol F., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chytka L., Cifuentes A., Contreras J.L., Cortina J., Costantini H., Dalchenko M., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Di Piano A., Di Pierro F., Di Pilato A., Di Tria R., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Eisenberger L., Elsässer D., Fallah Ramazani V., Ferrara G., Ferrarotto F., Fiasson A., Foffano L., Freixas Coromina L., Fröse S., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Gasbarra C., Gasparrini D., Geyer D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The first prototype of LST (LST-1) for the Cherenkov Telescope Array has been in commissioning phase since 2018 and already started scientific observations with the low energy threshold around a few tens of GeV. In 2021, LST-1 observed BL Lac following the alerts based on multi-wavelength observations and detected prominent gamma-ray flares. In addition to the daily flux variability, LST-1 also detected sub-hour-scale intra-night variability reaching 3–4 times higher than the gamma-ray flux from the Crab Nebula above 100 GeV. In this proceeding, we will report the analysis results of LST-1 observations of BL Lac in 2021, especially focusing on flux variability.

Low energy performance boost through a hardware stereoscopic trigger between CTA LST-1 and MAGIC

Baxter J., Barrio J.A., Bitossi M., Donini A., Mazin D., Paoletti R., Pérez Aguilera A., Tejedor Álvarez L., Abe H., Abe K., Abe S., Abhir J., Acciari V.A., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Aniello T., Ansoldi S., Antonelli L.A., Aramo C., Arbet-Engels A., Cornelia A., Artero M., Asano K., Aubert P., Baack D., Babić A., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Batkovic I., Becerra González J., Bednarek W., Bernardini E., Bernardos M.I., Bernete Medrano J., Berti A., Besenrieder J., Bhattacharjee P., Biederbeck N., Bigongiari C., Biland A., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bošnjak , Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Busetto G., Campoy-Ordaz A., Cardillo M., Caroff S., Carosi A., Carosi R., Carrasco M.S., Carretero-Castrillo M., Cassol F., Castro-Tirado A.J., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chilingarian A., Chytka L., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Costantini H., Covino S., D’Amico G., Dalchenko M., D’Elia V., Da Vela P., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delfino M., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M., Del Popolo A., Depaoli D., Di Piano A.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The next generation facility for gamma-ray ground-based observations is the Cherenkov Telescope Array (CTA) observatory, which comprises three types of imaging atmospheric Cherenkov telescopes (IACTs). The Large-Sized Telescopes (LSTs) of CTA are the largest telescope type with a mirror dish of 23 m diameter. They cover the low energy end of the accessible gamma-ray energies for IACTs, starting from about 20 GeV up to a few TeV. The first LST prototype, known as LST-1, was officially inaugurated at the Observatorio del Roque de Los Muchachos in La Palma (Canary Islands, Spain) in 2018 and has since performed calibration observations of various known gamma-ray sources. Additionally, the site houses the MAGIC telescopes, two 17 m IACTs situated approximately 100 m away from LST-1, which have been performing stereo observations since 2009. Currently, joint observations between LST-1 and MAGIC are being carried on, and the data taken independently by the two IACT systems is analyzed by combining events via software. However, this method increases the energy threshold, as it discards all but the relatively high-energy events triggered by all three telescopes. To address this issue, we have developed a novel hardware stereo trigger system between LST-1 and MAGIC, which is capable of handling events triggered by any-two out of the three telescopes. In this contribution, we will report on the performance estimation of joint LST-1 and MAGIC observations using the hardware trigger.

Long-term study of the intermittent extreme behaviour of 1ES 2344+514

Arbet-Engels A., Mondal H.A., Fukami S., D’Ammando F., Dorner D., Chatterjee R., Majumdar P., Manganaro M., Hovatta T., Das S., Raiteri C.M., Villata M., Perri M., Verrechia F., Leto C., Filippenko A., Zheng W., Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chatterjee R., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Extreme high-frequency-peaked BL Lac objects (EHBLs) are the most energetic persistent sources in the Universe. They are characterized by a spectral energy distribution (SED) featuring a synchrotron peak energy above 1 keV. 1ES 2344+514 is a blazar known to behave as an EHBL intermittently. Until now, its EHBL nature was only reported during flares, but a coherent picture is missing as unbiased monitoring campaigns are lacking. This work presents the longest observing campaign from radio to very-high-energy (VHE) frequencies performed so far on 1ES2344+514. Using observations during 2019-2021, we carry out a systematic investigation of the intermittent EHBL phases. Together with MAGIC, the dataset also includes X-ray observations from NuSTAR, XMM-Newton, and AstroSAT, providing an unprecedented determination of the two SED components. For the first time we report a clear EHBL behaviour during a low flux activity in 1ES 2344+514. It implies a significant hardening of the electron distribution inside the jet independent of flux. We also detect a bright X-ray state characterized by an unusually soft spectra, thus violating the harder-when-brighter relation typically found in blazars. The SED study further reveals an excess in the ultraviolet data with respect to the extrapolation of the X-ray spectrum, suggesting at least two regions contributing to the synchrotron flux. Finally we investigate a gamma-ray flare not accompanied by an X-ray counterpart. This peculiar outburst is interpreted using a time-dependent model involving two emitting components.

Long term study of the blazar S5 0716+714: investigating a turbulent jet at all wavelengths

Podobnik F., Manganaro M., Jormanainen J., Lindfors E., Bonnoli G., Paoletti R., Jorstad S., Kiehlmann S., Agudo I., Elsasser D., Lorey C., Raiteri C., Villata M., Redhead A.C., Marscher A., Abe H., Abe S., Abhir J., Acciari V.A., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The blazar S5 0716+714 is an intermediate BL Lacertae object remarkable for its variability in many energy bands. It was discovered by MAGIC in the very-high-energy (VHE) gamma-ray range in 2008. Later in 2015 an impressive electric vector polarization angle (EVPA) swing was detected in connection with a multiwavelength flaring event including the VHE gamma-ray band. This generated interest in further studies of the jet of this source and its electromagnetic emission at all wavelengths. Since then, MAGIC has monitored the source in coordination with other observatories and here we present the long-term study using data from 2015 to 2022 in a MWL context. The data set also includes the extraordinary flaring activity of 2017, so far the historical maximum detected for this source in the optical and VHE gamma-ray band.

Joint searches by FACT, H.E.S.S., MAGIC and VERITAS for VHE gamma-ray emission associated with neutrinos detected by IceCube

Schüssler F., Ashkar H., Bernardini E., Berti A., Bradascio F., Buson S., Dorner D., Jin W., Kukec Mezek G., Santander M., Satalecka K., Schleicher B., Senniappanh M., Viale I., Abhir J., Baack D., Balbo M., Biland A., Brand K., Bretz T., Buss J., Eisenberger L., Elsaesser D., Günther P., Hildebrand D., Mannheim K., Noethe M., Paravac A., Rhode W., Sliusar V., Hasan S., Walter R., Aharonian F., Ait Benkhali F., Alkan A., Aschersleben J., Backes M., Baktash A., Barbosa Martins V., Barnacka A., Barnard J., Batzofin R., Becherini Y., Beck G., Berge D., Bernlöhr K., Bi B., Böttcher M., Boisson C., Bolmont J., de Bony de Lavergne M., Borowska J., Bouyahiaoui M., Breuhaus M., Brose R., Brown A., Brun F., Bruno B., Bulik T., Burger-Scheidlin C., Bylund T., Cangemi F., Caroff S., Casanova S., Cecil R., Celic J., Cerruti M., Chambery P., Chand T., Chandra S., Chen A., Chibueze J., Chibueze O., Collins T., Cotter G., Cristofari P., Damascene Mbarubucyeye J., Davids I.D., Davies J., de Jonge L., Devin J., Djannati-Ataï A., Dmytriiev A., Doroshenko V., Dreyer L., Du Plessis L., Egberts K., Einecke S., Ernenwein J.P., Fegan S., Feijen K., de Clairfontaine G.F., Fontaine G., Lott F., Füßling M., Funk S., Gabici S., Gallant Y.A., Ghafourizadeh S., Giavitto G.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The sources of the astrophysical flux of high-energy neutrinos detected by IceCube are still largely unknown, but searches for temporal and spatial correlation between neutrinos and electromagnetic radiation are a promising approach in this endeavor. All major imaging atmospheric Cherenkov telescopes (IACTs) - FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program of target-of-opportunity observations of neutrino alerts issued by IceCube. These programs use several complementary neutrino alert streams. A publicly distributed alert stream is formed by individual high-energy neutrino candidate events of potentially astrophysical origin, such as IceCube-170922A (which could be linked to the flaring blazar TXS 0506+056). A privately distributed alert stream is formed by clusters of neutrino events in time and space around either pre-selected gamma-ray sources or anywhere in the sky. Here, we present joint searches for multi-wavelength emission associated with a set of IceCube alerts, both private and public, received through mid-January 2021. We will give an overview of the programs of the participating IACTs. We will showcase the various follow-up and data analysis strategies employed in response to the different alert types and various possible counterpart scenarios. Finally, we will present results from a combined analysis of the VHE gamma-ray observations obtained across all involved instruments, as well as relevant multi-wavelength data.

Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

Abe S., Berti A., Di Pierro F., López-Coto R., Moralejo A., Ohtani Y., Sitarek J., Strzys M., Suda Y., Vovk I., Abe H., Abe K., Abe S., Abhir J., Acciari V.A., Aguasca-Cabot A., Agudo I., Alvarez Crespo N., Aniello T., Ansoldi S., Antonelli L.A., Aramo C., Arbet-Engels A., Cornelia A., Artero M., Asano K., Aubert P., Baack D., Babić A., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M.I., Bernete Medrano J., Besenrieder J., Bhattacharjee P., Biederbeck N., Bigongiari C., Biland A., Bissaldi E., Blanch O., Bonnoli G., Bordas P., Bošnjak , Bulgarelli A., Burelli I., Burmistrov L., Buscemi M., Busetto G., Campoy-Ordaz A., Cardillo M., Caroff S., Carosi A., Carosi R., Carrasco M.S., Carretero-Castrillo M., Cassol F., Castro-Tirado A.J., Cauz D., Cerasole D., Ceribella G., Chai Y., Cheng K., Chiavassa A., Chikawa M., Chilingarian A., Chytka L., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Costantini H., Covino S., D’Amico G., Dalchenko M., D’Elia V., Da Vela P., Dazzi F., De Angelis A., de Bony de Lavergne M., De Lotto B., De Lucia M., de Menezes R., Del Peral L., Deleglise G., Delfino M., Delgado C., Delgado Mengual J., della Volpe D., Dellaiera M.

Proceedings of Science Vol. 444 2024.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations.

Transplanted Brazilian Portuguese in Japan Mobility, contact, and koine formation among Latin American immigrants

Matsumoto, K; Okumura, A; Matsuda, K

ASIA-PACIFIC LANGUAGE VARIATION Vol. 10 ( 1 ) page： 40 - 66 2024.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Asia-Pacific Language Variation

This paper explores an emerging Brazilian Portuguese koiné spoken among Brazilian-dominant Latin American immigrants in Japan's Greater Tokyo Area. It examines Strong-R (onset/r/) realizations by 79 speakers in the context of dialect and language contact within the diasporic setting. The results highlight (a) levelling and focussing towards [h] as a result of koineization and (b) early stages of the adoption of [ϕ], a xenolectal feature, resulting from contact with Japanese. The external and internal motivations for change towards [h] are identified as oca and supra oca levelling and drift. The transition to [ϕ], and its linguistic and social embedding, are discussed in terms of acquisition order, the structure of the Japanese kana syllabary, and speakers' social networks. The conclusion emphasizes the importance for koiné genesis of input dialects, ongoing language change in the homeland, the social meaning of variants in both pre- and post-contact societies, and speakers' social networks and mobilities.

DOI： 10.1075/aplv.21004.mat

GRB 221009A observations with LST-1 at VHE gamma rays

K. Abe, S. Abe, A. Abhishek, F. Acero, A. Aguasca-Cabot, I. Agudo, N. Alvarez Crespo, L. A. Antonelli, C. Aramo, A. Arbet-Engels, C. Arcaro, K. Asano, P. Aubert, A. Baktash, A. Bamba, A. Baquero Larriva, U. Barres de Almeida, J. A. Barrio, L. Barrios Jiménez, I. Batkovic, J. Baxter, J. Becerra González, E. Bernardini, J. Bernete Medrano, A. Berti, P. Bhattacharjee, C. Bigongiari, E. Bissaldi, O. Blanch, G. Bonnoli, P. Bordas, G. Brunelli, A. Bulgarelli, I. Burelli, L. Burmistrov, M. Buscemi, M. Cardillo, S. Caroff, A. Carosi, M. S. Carrasco, F. Cassol, N. Castrejón, D. Cauz, D. Cerasole, G. Ceribella, Y. Chai, K. Cheng, A. Chiavassa, M. Chikawa, G. Chon, L. Chytka, G. M. Cicciari, A. Cifuentes, J. L. Contreras, J. Cortina, H. Costantini, P. Da Vela, M. Dalchenko, F. Dazzi, A. De Angelis, M. de Bony de Lavergne, B. De Lotto, R. de Menezes, L. Del Peral, C. Delgado, J. Delgado Mengual, D. della Volpe, M. Dellaiera, A. Di Piano, F. Di Pierro, R. Di Tria, L. Di Venere, C. Díaz, R. M. Dominik, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsässer, G. Emery, J. Escudero, V. Fallah Ramazani, F. Ferrarotto, A. Fiasson, L. Foffano, L. Freixas Coromina, S. Fröse, Y. Fukazawa, R. Garcia López, C. Gasbarra, D. Gasparrini, D. Geyer, J. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinovic, R. Grau, D. Green

Proceedings of Science Vol. 461 2024.7

Language：English Publishing type：Research paper (international conference proceedings)

On October 9th, 2022, the brightest gamma-ray burst (GRB) since the first GRB observation in the late sixties was detected by the Fermi-GBM and Swift-BAT telescopes (GRB 221009A). The outstanding characteristics of this GRB triggered extensive follow-up observations of the source across all wavebands, including at very-high-energy (VHE) gamma rays with the Large-Sized Telescope prototype (LST-1) of the upcoming Cherenkov Telescope Array Observatory (CTAO). In this contribution, we present the analysis and results of the LST-1 observation campaign in October 2022, focusing on the data taken under nominal observing conditions and above 200 GeV.

Constraints on Lorentz invariance violation from the extraordinary Mrk 421 flare of 2014 using a novel analysis method Open Access

S. Abe, J. Abhir, A. Abhishek, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, M. Artero, K. Asano, A. Babić, A. Baquero, U. Barres de Almeida, J. A. Barrio, I. Batković, A. Bautista, J. Baxter, J. Becerra González, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Z. Bošnjak, E. Bronzini, I. Burelli, G. Busetto, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, Y. Chai, A. Cifuentes, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, G. D'Amico, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, R. de Menezes, A. Del Popolo, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsaesser, G. Emery, J. Escudero, L. Fariña, A. Fattorini, L. Foffano, L. Font, S. Fröse, S. Fukami, Y. Fukazawa, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinović, T. Gradetzke, R. Grau, D. Green, J. G. Green, P. Günther, D. Hadasch, A. Hahn, T. Hassan, L. Heckmann, J. Herrera, D. Hrupec, M. Hütten, R. Imazawa, K. Ishio, I. Jiménez Martínez, J. Jormanainen

Journal of Cosmology and Astroparticle Physics Vol. 2024 ( 7 ) 2024.7

Language：English Publishing type：Research paper (scientific journal)

The Lorentz Invariance Violation (LIV), a proposed consequence of certain quantum gravity (QG) scenarios, could instigate an energy-dependent group velocity for ultra-relativistic particles. This energy dependence, although suppressed by the massive QG energy scale E_QG, expected to be on the level of the Planck energy 1.22 × 1019 GeV, is potentially detectable in astrophysical observations. In this scenario, the cosmological distances traversed by photons act as an amplifier for this effect. By leveraging the observation of a remarkable flare from the blazar Mrk 421, recorded at energies above 100 GeV by the MAGIC telescopes on the night of April 25 to 26, 2014, we look for time delays scaling linearly and quadratically with the photon energies. Using for the first time in LIV studies a binned-likelihood approach we set constraints on the QG energy scale. For the linear scenario, we set 95% lower limits E_QG>2.7×1017 GeV for the subluminal case and E_QG> 3.6 ×1017 GeV for the superluminal case. For the quadratic scenario, the 95% lower limits for the subluminal and superluminal cases are E_QG>2.6 ×1010 GeV and E_QG>2.5×1010 GeV, respectively.

DOI： 10.1088/1475-7516/2024/07/044

Dark matter line searches with the Cherenkov Telescope Array Open Access

S. Abe, J. Abhir, A. Abhishek, F. Acero, A. Acharyya, R. Adam, A. Aguasca-Cabot, I. Agudo, A. Aguirre-Santaella, J. Alfaro, R. Alfaro, N. Alvarez-Crespo, R. Alves Batista, J. P. Amans, E. Amato, G. Ambrosi, L. Angel, C. Aramo, C. Arcaro, T. T.H. Arnesen, L. Arrabito, K. Asano, Y. Ascasibar, J. Aschersleben, H. Ashkar, M. Backes, A. Baktash, C. Balazs, M. Balbo, A. Baquero Larriva, V. Barbosa Martins, U. Barres De Almeida, J. A. Barrio, I. Batkovic, R. Batzofin, J. Baxter, J. Becerra González, G. Beck, W. Benbow, D. Berge, E. Bernardini, J. Bernete, K. Bernlöhr, A. Berti, B. Bertucci, P. Bhattacharjee, S. Bhattacharyya, C. Bigongiari, A. Biland, E. Bissaldi, J. Biteau, O. Blanch, J. Blazek, F. Bocchino, C. Boisson, J. Bolmont, G. Bonnoli, A. Bonollo, P. Bordas, Z. Bosnjak, E. Bottacini, M. Böttcher, T. Bringmann, E. Bronzini, R. Brose, A. M. Brown, G. Brunelli, A. Bulgarelli, T. Bulik, I. Burelli, L. Burmistrov, M. Burton, M. Buscemi, T. Bylund, J. Cailleux, A. Campoy-Ordaz, B. K. Cantlay, G. Capasso, A. Caproni, R. Capuzzo-Dolcetta, P. Caraveo, S. Caroff, A. Carosi, R. Carosi, E. Carquin, M. S. Carrasco, F. Cassol, L. Castaldini, N. Castrejon, A. J. Castro-Tirado, D. Cerasole, M. Cerruti, P. M. Chadwick, S. Chaty, A. W. Chen, M. Chernyakova, A. Chiavassa, J. Chudoba, L. Chytka, G. M. Cicciari

Journal of Cosmology and Astroparticle Physics Vol. 2024 ( 7 ) 2024.7

Language：English Publishing type：Research paper (scientific journal)

Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g. box-shaped spectra, that would likewise very clearly point to a particle dark matter origin.

DOI： 10.1088/1475-7516/2024/07/047

Insights into the broadband emission of the TeV blazar Mrk 501 during the first X-ray polarization measurements Open Access

S. Abe, J. Abhir, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, K. Asano, A. Babić, A. Baquero, U. Barres De Almeida, J. A. Barrio, I. Batković, A. Bautista, J. Baxter, J. Becerra González, W. Bednarek, E. Bernardini, M. Bernardos, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Bošnjak, I. Burelli, G. Busetto, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, G. Ceribella, Y. Chai, A. Cifuentes, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, G. D'Amico, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, R. De Menezes, A. Del Popolo, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, L. Di Venere, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsaesser, G. Emery, J. Escudero, L. Fariña, A. Fattorini, L. Foffano, L. Font, S. Fröse, Y. Fukazawa, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinović, T. Gradetzke, R. Grau, D. Green, J. G. Green, P. Günther, D. Hadasch, A. Hahn, T. Hassan, L. Heckmann, J. Herrera, D. Hrupec, M. Hütten, R. Imazawa, K. Ishio, I. Jiménez Martínez, T. Kayanoki, D. Kerszberg, G. W. Kluge, Y. Kobayashi, P. M. Kouch, H. Kubo

Astronomy and Astrophysics Vol. 685 2024.5

Language：English Publishing type：Research paper (scientific journal)

Aims. We present the first multiwavelength study of Mrk 501 that contains simultaneous very-high-energy (VHE) γ-ray observations and X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). Methods. We used radio-to-VHE data from a multiwavelength campaign carried out between March 1, 2022, and July 19, 2022 (MJD 59639 to MJD 59779). The observations were performed by MAGIC, Fermi-LAT, NuSTAR, Swift (XRT and UVOT), and several other instruments that cover the optical and radio bands to complement the IXPE pointings. We characterized the dynamics of the broadband emission around the X-ray polarization measurements through its multiband fractional variability and correlations, and compared changes observed in the polarization degree to changes seen in the broadband emission using a multi-zone leptonic scenario. Results. During the IXPE pointings, the VHE state is close to the average behavior, with a 0.2- 1 TeV flux of 20%- 50% of the emission of the Crab Nebula. Additionally, it shows low variability and a hint of correlation between VHE γ-rays and X-rays. Despite the average VHE activity, an extreme X-ray behavior is measured for the first two IXPE pointings, taken in March 2022 (MJD 59646 to 59648 and MJD 59665 to 59667), with a synchrotron peak frequency > 1 keV. For the third IXPE pointing, in July 2022 (MJD 59769 to 59772), the synchrotron peak shifts toward lower energies and the optical/X-ray polarization degrees drop. All three IXPE epochs show an atypically low Compton dominance in the γ-rays. The X-ray polarization is systematically higher than at lower energies, suggesting an energy stratification of the jet. While during the IXPE epochs the polarization angles in the X-ray, optical, and radio bands align well, we find a clear discrepancy in the optical and radio polarization angles in the middle of the campaign. Such results further support the hypothesis of an energy-stratified jet. We modeled broadband spectra taken simultaneous to the IXPE pointings, assuming a compact zone that dominates in the X-rays and the VHE band, and an extended zone stretching farther downstream in the jet that dominates the emission at lower energies. NuSTAR data allow us to precisely constrain the synchrotron peak and therefore the underlying electron distribution. The change between the different states observed in the three IXPE pointings can be explained by a change in the magnetization and/or the emission region size, which directly connects the shift in the synchrotron peak to lower energies with the drop in the polarization degree.

DOI： 10.1051/0004-6361/202348709

Constraints on axion-like particles with the Perseus Galaxy Cluster with MAGIC

Abe, H; Abe, S; Abhir, J; Acciari, VA; Agudo, I; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Artero, M; Asano, K; Baack, D; Babic, A; Baquero, A; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Burelli, I; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Ceribella, G; Chai, Y; Cifuentes, A; Cikota, S; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Del Popolo, A; Delgado, J; Mendez, CD; Depaoli, D; Di Pierro, F; Di Venere, L; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fukami, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, JG; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Herrera, J; Hrupec, D; Hütten, M; Imazawa, R; Inada, T; Iotov, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Lezáun, ML; Lamastra, A; Leone, F; Lindfors, E; Linhoff, L; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Martínez-Chicharro, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nakamori, T; Nanci, C; Nava, L; Neustroev, V; Nickel, L; Rosillo, MN; Nigro, C; Nikolic, L; Nilsson, K; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Pavlovic, D; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Tajima, H; Takahashi, M; Takeishi, R; Tavecchio, F; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Tosti, L; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Verguilov, V; Viale, I; Vigorito, CF; Vitale, V; Vovk, I; Walter, R; Will, M; Yamamoto, T

PHYSICS OF THE DARK UNIVERSE Vol. 44 2024.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Physics of the Dark Universe

Axion-like particles (ALPs) are pseudo-Nambu–Goldstone bosons that emerge in various theories beyond the standard model. These particles can interact with high-energy photons in external magnetic fields, influencing the observed gamma-ray spectrum. This study analyzes 41.3 h of observational data from the Perseus Galaxy Cluster collected with the MAGIC telescopes. We focused on the spectra the radio galaxy in the center of the cluster: NGC 1275. By modeling the magnetic field surrounding this target, we searched for spectral indications of ALP presence. Despite finding no statistical evidence of ALP signatures, we were able to exclude ALP models in the sub-micro electronvolt range. Our analysis improved upon previous work by calculating the full likelihood and statistical coverage for all considered models across the parameter space. Consequently, we achieved the most stringent limits to date for ALP masses around 50 neV, with cross sections down to gaγ=3×10−12 GeV−1.

DOI： 10.1016/j.dark.2024.101425

First characterization of the emission behavior of Mrk 421 from radio to very high-energy gamma rays with simultaneous X-ray polarization measurements Open Access

S. Abe, J. Abhir, V. A. Acciari, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet-Engels, C. Arcaro, M. Artero, K. Asano, A. Babić, A. Baquero, U. Barres de Almeida, J. A. Barrio, I. Batković, J. Baxter, J. Becerra González, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Bošnjak, I. Burelli, G. Busetto, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, G. Ceribella, Y. Chai, A. Cifuentes, S. Cikota, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, F. D'Ammando, G. D'Amico, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, R. de Menezes, A. Del Popolo, J. Delgado, C. Delgado Mendez, F. Di Pierro, L. Di Venere, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsaesser, G. Emery, J. Escudero, L. Fariña, A. Fattorini, L. Foffano, L. Font, S. Fröse, S. Fukami, Y. Fukazawa, R. J.García López, M. Garczarczyk, S. Gasparyan, M. Gaug, J. G.Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, N. Godinović, T. Gradetzke, R. Grau, D. Green, J. G. Green, P. Günther, D. Hadasch, A. Hahn, T. Hassan, L. Heckmann, J. Herrera, D. Hrupec, M. Hütten, R. Imazawa, T. Inada, K. Ishio, I. Jiménez Martínez, J. Jormanainen, D. Kerszberg, G. W. Kluge, Y. Kobayashi, P. M. Kouch

Astronomy and Astrophysics Vol. 684 2024.4

Language：English Publishing type：Research paper (scientific journal)

Aims. We have performed the first broadband study of Mrk 421 from radio to TeV gamma rays with simultaneous measurements of the X-ray polarization from IXPE. Methods. The data were collected as part of an extensive multiwavelength campaign carried out between May and June 2022 using MAGIC, Fermi-LAT, NuSTAR, XMM-Newton, Swift, and several optical and radio telescopes to complement IXPE data. Results. During the IXPE exposures, the measured 0.2-1 TeV flux was close to the quiescent state and ranged from 25% to 50% of the Crab Nebula without intra-night variability. Throughout the campaign, the very high-energy (VHE) and X-ray emission are positively correlated at a 4σ significance level. The IXPE measurements reveal an X-ray polarization degree that is a factor of 2-5 higher than in the optical/radio bands; that implies an energy-stratified jet in which the VHE photons are emitted co-spatially with the X-rays, in the vicinity of a shock front. The June 2022 observations exhibit a rotation of the X-ray polarization angle. Despite no simultaneous VHE coverage being available during a large fraction of the swing, the Swift-XRT monitoring reveals an X-ray flux increase with a clear spectral hardening. This suggests that flares in high synchrotron peaked blazars can be accompanied by a polarization angle rotation, as observed in some flat spectrum radio quasars. Finally, during the polarization angle rotation, NuSTAR data reveal two contiguous spectral hysteresis loops in opposite directions (clockwise and counterclockwise), implying important changes in the particle acceleration efficiency on approximately hour timescales.

DOI： 10.1051/0004-6361/202347988

The variability patterns of the TeV blazar PG 1553 + 113 from a decade of MAGIC and multiband observations

Abe H., Abe S., Abhir J., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres de Almeida U., Batković I., Baxter J., Becerra González J., Bernardini E., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Chai Y., Cifuentes A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D’Amico G., D’Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fukami S., Fukazawa Y., García López R.J., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Grau R., Green J.G., Hadasch D., Hahn A., Heckmann L., Herrera J., Hovatta T., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K., Jimenez Martínez I., Jormanainen J., Kerszberg D., Kluge G.W., Kobayashi Y., Kouch P.M., Kubo H., Kushida J., Láinez Lezáun M., Lamastra A., Leone F., Lindfors E.

Monthly Notices of the Royal Astronomical Society Vol. 529 ( 4 ) page： 3894 - 3911 2024.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Monthly Notices of the Royal Astronomical Society

PG 1553 + 113 is one of the few blazars with a convincing quasi-periodic emission in the gamma-ray band. The source is also a very high energy (VHE; >100 GeV) gamma-ray emitter. To better understand its properties and identify the underlying physical processes driving its variability, the MAGIC Collaboration initiated a multiyear, multiwavelength monitoring campaign in 2015 involving the OVRO 40-m and Medicina radio telescopes, REM, KVA, and the MAGIC telescopes, Swift and Fermi satellites, and the WEBT network. The analysis presented in this paper uses data until 2017 and focuses on the characterization of the variability. The gamma-ray data show a (hint of a) periodic signal compatible with literature, but the X-ray and VHE gamma-ray data do not show statistical evidence for a periodic signal. In other bands, the data are compatible with the gamma-ray period, but with a relatively high p-value. The complex connection between the low- and high-energy emission and the non-monochromatic modulation and changes in flux suggests that a simple one-zone model is unable to explain all the variability. Instead, a model including a periodic component along with multiple emission zones is required.

DOI： 10.1093/mnras/stae649

Performance and first measurements of the MAGIC stellar intensity interferometer Open Access

S. Abe, J. Abhir, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, M. Artero, K. Asano, A. Babić, A. Baquero, U. Barres De Almeida, J. A. Barrio, I. Batković, A. Bautista, J. Baxter, J. Becerra González, E. Bernardini, M. Bernardos, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Bošnjak, I. Burelli, G. Busetto, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, G. Ceribella, Y. Chai, A. Cifuentes, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, G. D'Amico, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, R. De Menezes, A. Del Popolo, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, L. Di Venere, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsaesser, G. Emery, J. Escudero, L. Fariña, A. Fattorini, L. Foffano, L. Font, S. Fröse, S. Fukami, Y. Fukazawa, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, J. G. Giesbrecht Pai V A, N. Giglietto, F. Giordano, P. Gliwny, T. Gradetzke, R. Grau, D. Green, J. G. Green, P. Günther, D. Hadasch, A. Hahn, T. Hassan, L. Heckmann, J. Herrera, D. Hrupec, M. Hütten, R. Imazawa, K. Ishio, I. Jiménez Martínez, J. Jormanainen, T. Kayanoki, D. Kerszberg, G. W. Kluge, Y. Kobayashi, P. M. Kouch, H. Kubo

Monthly Notices of the Royal Astronomical Society Vol. 529 ( 4 ) page： 4387 - 4404 2024.3

Language：English Publishing type：Research paper (scientific journal)

In recent years, a new generation of optical intensity interferometers has emerged, leveraging the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC telescopes host the MAGIC-SII system (Stellar Intensity Interferometer), implemented to investigate the feasibility and potential of this technique on IACTs. After the first successful measurements in 2019, the system was upgraded and now features a real-time, dead-time-free, 4-channel, GPU-based correlator. These hardware modifications allow seamless transitions between MAGIC's standard very-high-energy gamma-ray observations and optical interferometry measurements within seconds. We establish the feasibility and potential of employing IACTs as competitive optical Intensity Interferometers with minimal hardware adjustments. The measurement of a total of 22 stellar diameters are reported, 9 corresponding to reference stars with previous comparable measurements, and 13 with no prior measurements. A prospective implementation involving telescopes from the forthcoming Cherenkov Telescope Array Observatory's Northern hemisphere array, such as the first prototype of its Large-Sized Telescopes, LST-1, is technically viable. This integration would significantly enhance the sensitivity of the current system and broaden the UV-plane coverage. This advancement would enable the system to achieve competitive sensitivity with the current generation of long-baseline optical interferometers over blue wavelengths.

DOI： 10.1093/mnras/stae697

Silicon photomultipliers for the SST camera of the Cherenkov Telescope Array

Depaoli, D; Lapington, J; Leach, S; Okumura, A; Sofia, I; Tajima, H

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 1060 2024.3

The Cherenkov Telescope Array Observatory (CTAO) will be the major global observatory for gamma-ray astronomy over the next decade and beyond. It will consist of two arrays of telescopes of different sizes, one for each hemisphere, and will be sensitive to gamma rays in the energy range from a few tens of GeV to hundreds of TeV. The Small-Sized Telescopes (SSTs) are a crucial component of the southern array, as they will extend the sensitivity of the observatory to the highest energies. Their focal plane will be equipped with 2048 Silicon Photomultiplier (SiPM) pixels, each one read independently by a state-of-the-art full waveform sampling readout. These solid-state sensors offer advantages over the traditional photomultiplier tubes, such as lower operating voltage, higher photon detection efficiency, and tolerance to bright illumination. In particular, they are the best choice for a small and compact camera such as the SST one. After a detailed comparative study, LVR3-type SiPMs from Hamamatsu Photonics were selected, with an active area of 6 mm × 6 mm, a microcell of 50 μm and without a protective coating, for optimum performance. The sensors demonstrated to have a higher photon detection efficiency and a lower crosstalk compared to the competitors, alongside a low dark count rate. In this contribution, we present the selection process and the latest measurements performed on the SiPMs mounted on the SST Camera module.

DOI： 10.1016/j.nima.2023.169047

Multi-year characterisation of the broad-band emission from the intermittent extreme BL Lac 1ES 2344+514

Abe, H; Abe, S; Acciari, VA; Agudo, I; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Artero, M; Asano, K; Baack, D; Babic, A; Baquero, A; de Almeida, UB; Batkovic, I; Baxter, J; González, JB; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Burelli, I; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Chai, Y; Cifuentes, A; Cikota, S; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Ammando, F; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Del Popolo, A; Delfino, M; Delgado, J; Mendez, CD; Depaoli, D; Di Pierro, F; Di Venere, L; Prester, DD; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fukami, S; Fukazawa, Y; López, RJG; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Grau, R; Green, JG; Hadasch, D; Hahn, A; Heckmann, L; Herrera, J; Hrupec, D; Hütten, M; Imazawa, R; Inada, T; Iotov, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Lezáun, ML; Lamastra, A; Leone, F; Lindfors, E; Linho, L; Lombardi, S; Longo, F; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mariotti, M; Martínez, M; Martínez-Chicharro, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nakamori, T; Nanci, C; Neustroev, V; Nigro, C; Nikolic, L; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Pavlovic, D; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Sitarek, J; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Suda, Y; Tajima, H; Takeishi, R; Tavecchio, F; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Tosti, L; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Ventura, S; Verguilov, V; Viale, I; Vigorito, CF; Vitale, V; Walter, R; Wunderlich, C; Yamamoto, T; Perri, M; Verrecchia, F; Leto, C; Das, S; Chatterjee, R; Raiteri, CM; Villata, M; Semkov, E; Ibryamov, S; Bachev, R; Strigachev, A; Damljanovic, G; Vince, O; Jovanovic, MD; Stojanovic, M; Larionov, VM; Grishina, TS; Kopatskaya, EN; Larionova, EG; Morozova, DA; Savchenko, SS; Troitskiy, IS; Troitskaya, YV; Vasilyev, AA; Chen, WP; Hou, WJ; Lin, CS; Tsai, A; Jorstad, SG; Weaver, ZR; Acosta-Pulido, JA; Carnerero, MI; Carosati, D; Kurtanidze, SO; Kurtanidze, OM; Jordan, B; Ivanidze, RZ; Gazeas, K; Vrontaki, K; Hovatta, T; Liodakis, I; Readhead, ACS; Kiehlmann, S; Zheng, W; Filippenko, AV; Ramazani, VF

ASTRONOMY & ASTROPHYSICS Vol. 682 2024.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Aims. The BL Lac 1ES 2344+514 is known for temporary extreme properties characterised by a shift of the synchrotron spectral energy distribution (SED) peak energy νsynch;p above 1 keV. While those extreme states have only been observed during high flux levels thus far, additional multi-year observing campaigns are required to achieve a coherent picture. Here, we report the longest investigation of the source from radio to very high energy (VHE) performed so far, focussing on a systematic characterisation of the intermittent extreme states. Methods.We organised a monitoring campaign covering a 3-year period from 2019 to 2021.Morethan ten instruments participated in the observations in order to cover the emission from radio to VHE. In particular, sensitive X-ray measurements by XMM-Newton, NuSTAR, and AstroSat took place simultaneously with multi-hour MAGIC observations, providing an unprecedented constraint of the two SED components for this blazar. Results. While our results confirm that 1ES 2344+514 typically exhibits νsynch;p > 1 keV during elevated flux periods, we also find periods where the extreme state coincides with low flux activity. A strong spectral variability thus happens in the quiescent state, and is likely caused by an increase in the electron acceleration efficiency without a change in the electron injection luminosity. On the other hand, we also report a strong X-ray flare (among the brightest for 1ES 2344+514) without a significant shift of νsynch;p. During this particular flare, the X-ray spectrum is among the softest of the campaign. It unveils complexity in the spectral evolution, where the common harder-when-brighter trend observed in BL Lacs is violated. By combining Swift-XRT and Swift-UVOT measurements during a low and hard X-ray state, we find an excess of the UV flux with respect to an extrapolation of the X-ray spectrum to lower energies. This UV excess implies that at least two regions significantly contribute to the infrared/optical/ultraviolet/X-ray emission. Using the simultaneous MAGIC, XMM-Newton, NuSTAR, and AstroSat observations, we argue that a region possibly associated with the 10 GHz radio core may explain such an excess. Finally, we investigate a VHE flare, showing an absence of simultaneous variability in the 0.3-2 keV band. Using time-dependent leptonic modelling, we show that this behaviour, in contradiction to single-zone scenarios, can instead be explained by a two-component model.

DOI： 10.1051/0004-6361/202347845

MAGIC detection of GRB 201216C at z=1.1

Abe, H; Abe, S; Acciari, VA; Aguda, ; Aniello, T; Ansoldi, S; Antonelli, LA; Engels, AA; Arcaro, C; Artero, M; Asano, K; Baack, D; Babic, A; Baquero, A; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernete, J; Berti, A; Besenrieder, J; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Burelli, I; Busetto, G; Campoy-Ordaz, A; Carosi, A; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Ceribella, G; Chai, Y; Cifuentes, A; Cikota, S; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Del Popolo, A; Delfino, M; Delgado, J; Mendez, CD; Depaoli, D; Di Pierro, F; Di Venere, L; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fukami, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, JG; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Herrera, J; Hrupec, D; Hütten, M; Imazawa, R; Inada, T; Iotov, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kouch, PM; Kubo, H; Kushida, J; Lezáun, ML; Lamastra, A; Leone, F; Lindfors, E; Linhoff, L; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Lyard, E; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; González, MM; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Nanci, C; Nava, L; Neustroev, V; Rosillo, MN; Nigro, C; Nikolic, L; Nilsson, K; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Pavletic, L; Pavlovic, D; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Sahakyan, N; Saito, T; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sciaccaluga, A; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Tajima, H; Takahashi, M; Takeishi, R; Tavecchio, F; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Tosti, L; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Verguilov, V; Viale, I; Vigorito, CF; Vitale, V; Vovk, I; Walter, R; Will, M; Yamamoto, T; Gomboc, A; Jordana-Mitjans, N; Melandri, A; Mundell, CG; Shrestha, M; Steele, IA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 527 ( 3 ) page： 5856 - 5867 2024.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Monthly Notices of the Royal Astronomical Society

Gamma-ray bursts (GRBs) are explosive transient events occurring at cosmological distances, releasing a large amount of energy as electromagnetic radiation over several energy bands. We report the detection of the long GRB 201216C by the MAGIC telescopes. The source is located at z = 1.1 and thus it is the farthest one detected at very high energies. The emission above 70 GeV of GRB 201216C is modelled together with multiwavelength data within a synchrotron and synchrotron self-Compton (SSC) scenario. We find that SSC can explain the broad-band data well from the optical to the very-high-energy band. For the late-time radio data, a different component is needed to account for the observed emission. Differently from previous GRBs detected in the very-high-energy range, the model for GRB 201216C strongly favours a wind-like medium. The model parameters have values similar to those found in past studies of the afterglows of GRBs detected up to GeV energies.

DOI： 10.1093/mnras/stad2958

Performance of the MAGIC stellar intensity interferometer and expansion to MAGIC + CTAO-LST1 stellar intensity interferometer

Cifuentes A., Acciari V.A., Barnes F., Chon G., Colombo E., Cortina J., Delgado C., Díaz C., Fiori M., Fink D., Hassan T., Martínez I.J., Jorge I., Kerszberg D., Lyard E., Martínez G., Mirzoyan R., Polo M., Produit N., Rodríguez-Vázquez J.J., Saha P., Schweizer T., Strom D., Walter R., Wunderlich C.W., Abe K., Abe S., Abhir J., Abhishek A., Aguasca-Cabot A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Engels A.A., Arcaro C., Artero M., Asano K., Babić A., de Almeida U.B., Barrio J.A., Batković I., Bautista A., Baxter J., González J.B., Bednarek W., Bernardini E., Bernete J., Berti A., Besenrieder J., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Bronzini E., Burelli I., Busetto G., Campoy-Ordaz A., Carosi A., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Cerasole D., Ceribella G., Chai Y., Chilingarian A., Contreras J.L., Covino S., D'Amico G., D'Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., de Menezes R., Delfino M., Delgado J., Mendez C.D., Di Pierro F., Di Tria R., Di Venere L., Prester D.D., Donini A., Dorner D., Doro M., Elsaesser D., Escudero J., Fariña L., Fattorini A., Foffano L., Font L., Fröse S., Fukami S., Fukazawa Y., López R.J.G., Garczarczyk M., Gasparyan S., Gaug M., Paiva J.G.G.

Proceedings of SPIE - The International Society for Optical Engineering Vol. 13095 2024

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of SPIE - The International Society for Optical Engineering

A new generation of optical intensity interferometers are emerging in recent years taking advantage of the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC SII (Stellar Intensity Interferometer) in La Palma, Spain, has been operating since its first successful measurements in 2019 and its current design allows it to operate regularly. The current setup is ready to follow up on bright optical transients, as changing from regular gamma-ray observations to SII mode can be done in a matter of minutes. A paper studying the system performance, first measurements and future upgrades has been recently published. MAGIC SII's first scientific results are the measurement of the angular size of 22 stars, 13 of which with no previous measurements in the B band. More recently the Large Sized Telescope prototype from the Cherenkov Telescope Array Observatory (CTAOLST1) has been upgraded to operate together with MAGIC as a SII, leading to its first correlation measurements at the beginning of 2024. MAGIC+CTAO-LST1 SII will be further upgraded by adding the remaining CTAO-LSTs at the north site to the system (which are foreseen to be built by the end of 2025). MAGIC+CTAO-LST1 SII shows a feasible technical solution to extend SII to the whole CTAO.

DOI： 10.1117/12.3016905

Status of the Small-Sized Telescopes programme for the Cherenkov Telescope Array Observatory

Trois A., Dournaux J., Scuderi S., White R., Tagliaferri G., Proserpio L., Tosti G., Bruno P., Cailleux J., Conforti V., El Mouden A., De Frondat F., Gargano C., Germani S., Gianotti F., Giavitto G., Giordano V., Grassi L., Iovenitti S., Laporte P., La Palombara N., Lessio L., Leto G., Marchetti A., Millul R., Molfese C., Russo F., Saturni F., Sironi G., Antonelli A., Funk S., Hinton J., Pareschi G., Sol H., Able M., Attinà P., Barcelo M., Baryshev A., Chadwick P., Depaoli D., Einecke S., Lapington J., Lee S., Okumura A., Rol E., Rowell G., Schaefer J., Sofia I., Tajima H., Watson J., Wohlleben F., Zanmar Sanchez R., Zink A., Balbo M., Bang S., Bekema M., Bellassai G., Berge D., Bigongiari C., Bonnoli G., Brown A., Bulgarelli A., Cappi M., Caraveo P., Cotter G., Cristofari P., Falceta-Gonçalves D., De Gouveia Dal Pino E., De Simone N., del Valle M.V., Fermino C., Giuliani A., Greenshaw T., Kowal G., Lloyd S., Lombardi S., Lucarelli F., Martinetti E., Mineo T., Nayak A., Oughton W., Penno M., Righi C., Ross D., Rulten C., Santos-Lima R., Schwab B., Sliusar V., Stamerra A., Takahashi M., Tavecchio F., Vecchi M., Vercellone S., Vink J., Walter R., Zampieri L., Zech A.

Proceedings of SPIE - The International Society for Optical Engineering Vol. 13094 2024

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of SPIE - The International Society for Optical Engineering

The Cherenkov Telescope Array Observatory (CTAO) will include telescopes of three different sizes, the smallest of which are the Small-Sized Telescopes (SSTs). In particular, the SSTs will be installed at the southern site of CTAO, on the Chilean Andes, and will cover the highest energy range of CTAO (up to ~300 TeV). The SSTs are developed by an international consortium of institutes that will provide them as an in-kind contribution to CTAO. The optical design of the SSTs is based on a Schwarzschild-Couder-like dual-mirror polynomial configuration, with a primary aperture of 4.3m diameter. They are equipped with a focal plane camera based on SiPM detectors covering a field of view of ~9°. The preliminary design of the SST telescopes was evaluated and approved during the Product Review (PR) organised with CTAO in February 2023. The SST project is now going through a consolidation phase leading to the finalisation and submission of the final design to the Critical Design Review (CDR), expected to occur late 2024, after which the production and construction of the telescopes will begin leading to a delivery of the telescopes to CTAO southern site starting at the end of 2025-early 2026 onward. In this contribution we will present the progress of the SST programme, including the results of the PDR, the consolidation phase of the project and the plan up to the on-site integration of the telescopes.

DOI： 10.1117/12.3019790

Performance of the joint LST-1 and MAGIC observations evaluated with Crab Nebula data

Abe, H; Abe, K; Abe, S; Acciari, VA; Aguasca-Cabot, A; Agudo, I; Crespo, NA; Aniello, T; Ansoldi, S; Antonelli, LA; Aramo, C; Arbet-Engels, A; Arcaro, C; Artero, M; Asano, K; Aubert, P; Baack, D; Babic, A; Baktash, A; Bamba, A; Larriva, AB; Baroncelli, L; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernardos, MI; Medrano, JB; Berti, A; Besenrieder, J; Bhattacharjee, P; Biederbeck, N; Bigongiari, C; Biland, A; Bissaldi, E; Blanch, O; Bonnoli, G; Bordas, P; Bosnjak, Z; Bulgarelli, A; Burelli, I; Burmistrov, L; Buscemi, M; Busetto, G; Ordaz, AC; Cardillo, M; Caroff, S; Carosi, A; Carosi, R; Carrasco, MS; Carretero-Castrillo, M; Cassol, F; Castro-Tirado, AJ; Cauz, D; Cerasole, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chytka, L; Cifuentes, A; Cikota, S; Colombo, E; Contreras, JL; Cornelia, A; Cortina, J; Costantini, H; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dalchenko, M; Dazzi, F; De Angelis, A; de Lavergne, MD; De Lotto, B; De Lucia, M; de Menezes, R; Del Peral, L; Del Popolo, A; Deleglise, G; Delfino, M; Mendez, CD; Mengual, JD; della Volpe, D; Dellaiera, M; Depaoli, D; De Angelis, A; Di Piano, A; Di Pierro, F; Di Pilato, A; Di Tria, R; Di Venere, L; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Díaz, C; Eisenberger, L; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Fariña, L; Fattorini, A; Ferrara, G; Ferrarotto, F; Fiasson, A; Foffano, L; Font, L; Coromina, LF; Fröse, S; Fukami, S; Fukazawa, Y; López, RJG; Garcia, E; Garczarczyk, M; Gasbarra, C; Gasparrini, D; Gasparyan, S; Gaug, M; Geyer, D; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, JG; Gunji, S; Günther, P; Hackfeld, J; Hadasch, D; Hahn, A; Hashiyama, K; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Hütten, M; Iarlori, M; Imazawa, R; Inada, T; Inome, Y; Ioka, K; Iori, M; Iotov, R; Ishio, K; Jacquemont, M; Martínez, IJ; Jobst, E; Jormanainen, J; Jurysek, J; Kagaya, M; Karas, V; Katagiri, H; Kataoka, J; Kerszberg, D; Kluge, GW; Kobayashi, Y; Kohri, K; Kong, A; Kouch, PM; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Le Flour, T; Leone, F; Lindfors, E; Linhoff, L; Linhoff, M; Lombardi, S; Longo, F; Loporchio, S; Lorini, A; Bahilo, JL; Luque-Escamilla, PL; Lyard, E; Lezáun, ML; López-Coto, R; López-Moya, M; López-Oramas, A; Fraga, BMD; Majumdar, P; Makariev, M; Mandat, D; Maneva, G; Manganaro, M; Mangano, S; Mang, N; Manicò, G; Mannheim, K; Mariotti, M; Marquez, P; Marsella, G; Martinez, O; Martínez, G; Martínez, M; Martí, J; Mas-Aguilar, A; Maurin, G; Mazin, D; Menchiari, S; Mender, S; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Micanovic, S; González, MM; Molina, E; Mondal, HA; Montaruli, T; Monteiro, I; Moralejo, A; Morcuende, D; Morselli, A; Moya, V; Muraishi, H; Murase, K; Nagataki, S; Nakamori, T; Nanci, C; Neronov, A; Neustroev, V; Nickel, L; Rosillo, MN; Nigro, C; Nikolic, L; Nilsson, K; Nishijima, K; Ekoume, TN; Noda, K; Nosek, D; Nozaki, S; Ohishi, M; Ohtani, Y; Oka, T; Okumura, A; Orito, R; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pavletic, L; Pech, M; Pecimotika, M; Peresano, M; Persic, M; Pfeiffle, F; Pietropaolo, E; Pihet, M; Pirola, G; Plard, C; Podobnik, F; Poireau, V; Polo, M; Pons, E; Moroni, PGP; Prandini, E; Prast, J; Principe, G; Priyadarshi, C; Prouza, M; Rando, R; Rhode, W; Ribó, M; Rico, J; Righi, C; Rizi, V; Fernandez, GR; Frías, MDR; Sahakyan, N; Saito, T; Sakurai, S; Sanchez, DA; Satalecka, K; Sato, M; Sato, Y; Saturni, FG; Savchenko, V; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Sciaccaluga, A; Siegert, T; Silvia, R; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suutarinen, S; Saric, T; Tajima, H; Takahashi, H; Takahashi, M; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Tavecchio, F; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Tosti, L; Travnicek, P; Truzzi, S; Tutone, A; Ubach, S; Vacula, M; Vallania, P; van Scherpenberg, J; Acosta, MV; Ventura, S; Verguilov, V; Viale, I; Vigliano, A; Vigorito, CF; Visentin, E; Vitale, V; Voutsinas, G; Vovk, I; Vuillaume, T; Acosta, M; Walter, R; Wei, Z; Will, M; Yamamoto, T; Yamazaki, R; Yoshida, T; Yoshikoshi, T; Zywucka, N

ASTRONOMY & ASTROPHYSICS Vol. 680 2023.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Aims. Large-Sized Telescope 1 (LST-1), the prototype for the Large-Sized Telescope at the upcoming Cherenkov Telescope Array Observatory, is concluding its commissioning phase at the Observatorio del Roque de los Muchachos on the island of La Palma. The proximity of LST-1 to the two MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes makes it possible to carry out observations of the same gamma-ray events with both systems. Methods. We describe the joint LST-1+MAGIC analysis pipeline and used simultaneous Crab Nebula observations and Monte Carlo simulations to assess the performance of the three-telescope system. The addition of the LST-1 telescope allows for the recovery of events in which one of the MAGIC images is too dim to survive analysis quality cuts. Results. Thanks to the resulting increase in the collection area and stronger background rejection, we found a significant improvement in sensitivity, allowing for the detection of 30% weaker fluxes in the energy range between 200 GeV and 3 TeV. The spectrum of the Crab Nebula, reconstructed in the energy range between ∼60 GeV and ∼10 TeV, is in agreement with previous measurements.

DOI： 10.1051/0004-6361/202346927

Star tracking for pointing determination of Imaging Atmospheric Cherenkov Telescopes

Abe, K; Abe, S; Aguasca-Cabot, A; Agudo, I; Crespo, NA; Antonelli, LA; Aramo, C; Arbet-Engels, A; Cornelia, A; Artero, M; Asano, K; Aubert, P; Baktash, A; Bamba, A; Larriva, AB; Baroncelli, L; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; Gonzalez, JB; Bernardini, E; Bernardos, M; Medrano, JB; Berti, A; Bhattacharjee, P; Biederbeck, N; Bigongiari, C; Bissaldi, E; Blanch, O; Bonnoli, G; Bordas, P; Bulgarelli, A; Burelli, ; Burmistrov, L; Buscemi, M; Cardillo, M; Caroff, S; Carosi, A; Cassol, F; Cauz, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chytka, L; Cifuentes, A; Contreras, JL; Cortina, J; Costantini, H; Dalchenko, M; De Angelis, A; de Lavergne, MD; De Lotto, B; de Menezes, R; Deleglise, G; Delgado, C; Mengual, JD; della Volpe, D; Dellaiera, M; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Diaz, C; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Ferrara, G; Ferrarotto, F; Fiasson, A; Coromina, LF; Fröse, S; Fukami, S; Fukazawa, Y; Garcia, E; Lopez, RG; Gasbarra, C; Gasparrini, D; Geyer, D; Paiva, JG; Giglietto, N; Giordano, F; Giro, E; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, J; Gunji, S; Guenther, P; Hackfeld, J; Hadasch, D; Hahn, A; Hashiyama, K; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Hütten, M; Iarlori, M; Imazawa, R; Inada, T; Inome, Y; Ioka, K; Iori, M; Ishio, K; Jacquemont, M; Martinez, IJ; Jurysek, J; Kagaya, M; Karas, V; Katagiri, H; Kataoka, J; Kerszberg, D; Kobayashi, Y; Kohri, K; Kong, A; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Le Flour, T; Linhoff, M; Longo, F; Lopez-Coto, R; Lopez-Oramas, A; Loporchio, S; Lorini, A; Luque-Escamilla, PL; Majumdar, P; Makariev, M; Mandat, D; Manganaro, M; Manico, G; Mannheim, K; Mariotti, M; Marquez, P; Marsella, G; Marti, J; Martinez, O; Martinez, G; Martinez, M; Mas-Aguilar, A; Maurin, G; Mazin, D; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Gonzalez, MM; Molina, E; Montaruli, T; Monteiro, I; Moralejo, A; Morcuende, D; Morselli, A; Muraishi, H; Murase, K; Nagataki, S; Nakamori, T; Nickel, L; Nievas, M; Nishijima, K; Noda, K; Nosek, D; Nozaki, S; Ohishi, M; Ohtani, Y; Oka, T; Okumura, A; Orito, R; Otero-Santos, J; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pech, M; Pecimotika, M; Peresano, M; Pfeiffle, F; Pietropaolo, E; Pirola, G; Plard, C; Podobnik, F; Poireau, ; Polo, M; Pons, E; Prandini, E; Prast, J; Principe, G; Priyadarshi, C; Prouza, M; Rando, R; Rhode, W; Ribo, M; Rizi, V; Fernandez, GR; Saito, T; Sakurai, S; Sanchez, DA; Saric, T; Sato, Y; Saturni, FG; Schleicher, B; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Sato, M; Siegert, T; Silvia, R; Sitarek, J; Sliusar, V; Spolon, A; Striskovic, J; Strzys, M; Suda, Y; Tajima, H; Takahashi, H; Takahashi, M; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Travnicek, P; Truzzi, S; Tutone, A; Vacula, M; Vallania, P; van Scherpenberg, J; Acosta, MV; Viale, ; Vigliano, A; Vigorito, CF; Vitale, V; Voutsinas, G; Vovk, I; Vuillaume, T; Walter, R; Wei, Z; Will, M; Yamamoto, T; Yamazaki, R; Yoshida, T; Yoshikoshi, T; Zywucka, N

ASTRONOMY & ASTROPHYSICS Vol. 679 2023.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

We present a novel approach to the determination of the pointing of Imaging Atmospheric Cherenkov Telescopes (IACTs) using the trajectories of the stars in their camera s field of view. The method starts with the reconstruction of the star positions from the Cherenkov camera data, taking into account the point spread function of the telescope, to achieve a satisfying reconstruction accuracy of the pointing position. A simultaneous fit of all reconstructed star trajectories is then performed with the orthogonal distance regression (ODR) method. ODR allows us to correctly include the star position uncertainties and use the time as an independent variable. Having the time as an independent variable in the fit makes it better suitable for various star trajectories. This method can be applied to any IACT and requires neither specific hardware nor interface or special data-taking mode. In this paper, we use the Large-Sized Telescope (LST) data to validate it as a useful tool to improve the determination of the pointing direction during regular data taking. The simulation studies show that the accuracy and precision of the method are comparable with the design requirements on the pointing accuracy of the LST (=14''). With the typical LST event acquisition rate of 10 kHz, the method can achieve up to 50 Hz pointing monitoring rate, compared to O(1) Hz achievable with standard techniques. The application of the method to the LST prototype (LST-1) commissioning data shows the stable pointing performance of the telescope.

DOI： 10.1051/0004-6361/202347128

Observations of the Crab Nebula and Pulsar with the Large-sized Telescope Prototype of the Cherenkov Telescope Array

Abe, H; Abe, K; Abe, S; Aguasca-Cabot, A; Agudo, ; Crespo, NA; Antonelli, LA; Aramo, C; Arbet-Engels, A; Arcaro, C; Artero, M; Asano, K; Aubert, P; Baktash, A; Bamba, A; Larriva, AB; Baroncelli, L; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bernardini, E; Bernardos, MI; Medrano, JB; Berti, A; Bhattacharjee, P; Biederbeck, N; Bigongiari, C; Bissaldi, E; Blanch, O; Bonnoli, G; Bordas, P; Borghese, A; Bulgarelli, A; Burelli, I; Buscemi, M; Cardillo, M; Caroff, S; Carosi, A; Cassol, F; Cauz, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chytka, L; Cifuentes, A; Contreras, JL; Cortina, J; Costantini, H; D'Amico, G; Dalchenko, M; De Angelis, A; de Lavergne, MD; de Lotto, B; de Menezes, R; Deleglise, G; Delgado, C; Mengual, JD; della Volpe, D; Dellaiera, M; Depaoli, D; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Díaz, C; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Ferrara, G; Ferrarotto, F; Fiasson, A; Coromina, LF; Fröse, S; Fukami, S; Fukazawa, Y; Garcia, E; López, RG; Gasbarra, C; Gasparrini, D; Geyer, F; Paiva, JG; Giglietto, N; Giordano, F; Giro, E; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, J; Gunji, S; Hackfeld, J; Hadasch, D; Hahn, A; Hashiyama, K; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Hütten, M; Iarlori, M; Imazawa, R; Inada, T; Inome, Y; Ioka, K; Iori, M; Ishio, K; Iwamura, Y; Jacquemont, M; Martinez, IJ; Jurysek, J; Kagaya, M; Karas, V; Katagiri, H; Kataoka, J; Kerszberg, D; Kobayashi, Y; Kong, A; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Le Flour, T; Linhoff, M; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Luque-Escamilla, PL; Majumdar, P; Makariev, M; Mandat, D; Manganaro, M; Manicò, G; Mannheim, K; Mariotti, M; Marquez, P; Marsella, G; Martí, J; Martinez, O; Martínez, G; Martínez, M; Marusevec, P; Mas-Aguilar, A; Maurin, G; Mazin, D; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Gonzalez, MM; Molina, E; Montaruli, T; Monteiro, I; Moralejo, A; Morcuende, D; Morselli, A; Mrakovcic, K; Murase, K; Nagai, A; Nagataki, S; Nakamori, T; Nickel, L; Nievas, M; Nishijima, K; Noda, K; Nosek, D; Nozaki, S; Ohishi, M; Ohtani, Y; Oka, T; Okazaki, N; Okumura, A; Orito, R; Otero-Santos, J; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pech, M; Pecimotika, M; Peresano, M; Pérez, A; Pietropaolo, E; Pirola, G; Plard, C; Podobnik, F; Poireau, V; Polo, M; Pons, E; Prandini, E; Prast, J; Principe, G; Priyadarshi, C; Prouza, M; Rando, R; Rhode, W; Ribó, M; Rizi, V; Fernandez, GR; Ruíz, JE; Saito, T; Sakurai, S; Sanchez, DA; Saric, T; Sato, Y; Saturni, FG; Schleicher, B; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Arroyo, MS; Silvia, R; Sitarek, J; Sliusar, V; Spolon, A; Striskovic, J; Strzys, M; Suda, Y; Sunada, Y; Tajima, H; Takahashi, H; Takahashi, M; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Tejedor, LA; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Travnicek, P; Truzzi, S; Tutone, A; Uhlrich, G; Vacula, M; Vallania, P; van Scherpenberg, J; Acosta, MV; Verguilov, V; Viale, I; Vigliano, A; Vigorito, CF; Vitale, V; Voutsinas, G; Vovk, I; Vuillaume, T; Walter, R; Will, M; Yamamoto, T; Yamazaki, R; Yoshida, T; Yoshikoshi, T; Zywucka, N; Bernlöhr, K; Gueta, O; Kosack, K; Maier, G; Watson, J

ASTROPHYSICAL JOURNAL Vol. 956 ( 2 ) 2023.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal

The Cherenkov Telescope Array (CTA) is a next-generation ground-based observatory for gamma-ray astronomy at very high energies. The Large-Sized Telescope prototype (LST-1) is located at the CTA-North site, on the Canary Island of La Palma. LSTs are designed to provide optimal performance in the lowest part of the energy range covered by CTA, down to ≃20 GeV. LST-1 started performing astronomical observations in 2019 November, during its commissioning phase, and it has been taking data ever since. We present the first LST-1 observations of the Crab Nebula, the standard candle of very-high-energy gamma-ray astronomy, and use them, together with simulations, to assess the performance of the telescope. LST-1 has reached the expected performance during its commissioning period—only a minor adjustment of the preexisting simulations was needed to match the telescope’s behavior. The energy threshold at trigger level is around 20 GeV, rising to ≃30 GeV after data analysis. Performance parameters depend strongly on energy, and on the strength of the gamma-ray selection cuts in the analysis: angular resolution ranges from 0.°12-0.°40, and energy resolution from 15%-50%. Flux sensitivity is around 1.1% of the Crab Nebula flux above 250 GeV for a 50 hr observation (12% for 30 minutes). The spectral energy distribution (in the 0.03-30 TeV range) and the light curve obtained for the Crab Nebula agree with previous measurements, considering statistical and systematic uncertainties. A clear periodic signal is also detected from the pulsar at the center of the Nebula.

DOI： 10.3847/1538-4357/ace89d

Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants

Acero, F; Acharyya, A; Adam, R; Aguasca-Cabot, A; Agudo, I; Aguirre-Santaella, A; Alfaro, J; Aloisio, R; Crespo, NA; Batista, RA; Amati, L; Amato, E; Ambrosi, G; Angüner, EO; Aramo, C; Arcaro, C; Armstrong, T; Asano, K; Ascasibar, Y; Aschersleben, J; Backes, M; Baktash, A; Balazs, C; Balbo, M; Ballet, J; Larriva, AB; Martins, VB; de Almeida, UB; Barrio, JA; Bastieri, D; Baxter, JR; Tjus, JB; Benbow, W; Bernardos-Martín, MI; Bernete, J; Berti, A; Bertucci, B; Beshley, V; Bhattacharjee, P; Bhattacharyya, S; Biland, A; Bissaldi, E; Biteau, J; Blanch, O; Bordas, P; Bottacini, E; Bregeon, J; Brose, R; Bucciantini, N; Bulgarelli, A; Capasso, M; Dolcetta, RAC; Caraveo, P; Cardillo, M; Carosi, R; Casanova, S; Cascone, E; Cassol, F; Catalani, F; Cerruti, M; Chadwick, P; Chaty, S; Chen, A; Chernyakova, M; Chiavassa, A; Chudoba, J; Coimbra-Araujo, C; Conforti, V; Contreras, JL; Costa, A; Costantini, H; Cristofari, P; Crocker, R; D'Amico, G; D'Ammando, F; De Angelis, A; De Caprio, V; Dal Pino, EMD; Wilhelmi, ED; de Souza, V; Delgado, C; della Volp, D; Depaoli, D; Di Girolamo, T; Di Pierro, F; Di Tria, R; Di Venere, L; Diebold, S; Djuvsland, JI; Donini, A; Doro, M; Dos Anjos, RDC; Dwarkadas, VV; Einecke, S; Elsässer, D; Emery, G; Evoli, C; Falceta-Goncalves, D; Fedorova, E; Fegan, S; Ferrand, G; Fiandrini, E; Filipovic, M; Fioretti, V; Fiori, M; Foffano, L; Fontaine, G; Fukami, S; Galanti, G; Galaz, G; Gammaldi, V; Gasbarra, C; Ghalumyan, A; Ghirlanda, G; Giarrusso, M; Giavitto, G; Giglietto, N; Giordano, F; Giroletti, M; Giuliani, A; Giunti, L; Godinovic, N; Coelho, JG; Gréaux, L; Green, D; Grondin, MH; Gueta, O; Gunji, S; Hassan, T; Heller, M; Hernández-Cadena, S; Hinton, J; Hnatyk, B; Hnatyk, R; Hoffmann, D; Hofmann, W; Holder, J; Horan, D; Horvath, P; Hrabovsky, M; Hrupec, D; Inada, T; Incardona, F; Inoue, S; Ishio, K; Jamrozy, M; Janecek, P; Martínez, IJ; Jin, W; Jung-Richardt, I; Jurysek, J; Kaaret, P; Karas, V; Katz, U; Kerszberg, D; Khélifi, B; Kieda, DB; Kissmann, R; Kleiner, T; Kluge, G; Kluzniak, W; Knödlseder, J; Kobayashi, Y; Kohri, K; Komin, N; Kornecki, P; Kubo, H; La Palombara, N; Láinez, M; Lamastra, A; Lapington, J; Lemoine-Goumard, M; Lenain, JP; Leone, F; Leto, G; Leuschner, F; Lindfors, E; Liodakis, I; Lohse, T; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Luque-Escamilla, PL; Macias, O; Mackey, J; Majumdar, P; Mandat, D; Manganaro, M; Manicò, G; Marconi, M; Martí, J; Martínez, G; Martinez, M; Martinez, O; Mello, AJTS; Menchiari, S; Meyer, DMA; Micanovic, S; Miceli, D; Miceli, M; Michalowski, J; Miener, T; Miranda, JM; Mitchell, A; Mode, B; Moderski, R; Mohrmann, L; Molina, E; Montaruli, T; Morcuende, D; Morlino, G; Morselli, A; Mosè, M; Moulin, E; Mukherjee, R; Munari, K; Murach, T; Nagai, A; Nagataki, S; Nemmen, R; Niemiec, J; Nieto, D; Rosillo, MN; Nikolajuk, M; Nishijima, K; Noda, K; Novosyadlyj, B; Nozaki, S; Ohishi, M; Ohm, S; Ohtani, Y; Okumura, A; Olmi, B; Ong, RA; Orienti, M; Orito, R; Orlandini, M; Orlando, E; Orlando, S; Ostrowski, M; Oya, I; Pantaleo, FR; Paredes, JM; Patricelli, B; Pecimotika, M; Peresano, M; Pérez-Romero, J; Persic, M; Petruk, O; Piano, G; Pietropaolo, E; Pirola, G; Pittori, C; Pohl, M; Ponti, G; Prandini, E; Principe, G; Priyadarshi, C; Pueschel, E; Pühlhofer, G; Pumo, ML; Quirrenbach, A; Rando, R; Razzaque, S; Reichherzer, P; Reimer, A; Reimer, O; Renaud, M; Reposeur, T; Ribó, M; Richtler, T; Rico, J; Rieger, F; Rigoselli, M; Riitano, L; Rizi, V; Roache, E; Romano, P; Romeo, G; Rosado, J; Rowell, G; Rudak, B; Sadeh, I; Safi-Harb, S; Saha, L; Sailer, S; Sánchez-Conde, M; Sarkar, S; Satalecka, K; Saturni, FG; Scherer, A; Schovánek, P; Schussler, F; Schwanke, U; Scuderi, S; Seglar-Arroyo, M; Sergijenko, O; Servillat, M; Shang, RY; Sharma, P; Siejkowski, H; Sliusar, V; Slowikowska, A; Sol, H; Specovius, A; Spencer, ST; Spengler, G; Stamerra, A; Stanic, S; Starecki, T; Starling, R; Stolarczyk, T; Pereira, LAS; Suda, Y; Suomijarvi, T; Sushch, I; Tajima, H; Tam, PHT; Tanaka, SJ; Tavecchio, F; Testa, V; Tian, W; Tibaldo, L; Torres, DF; Tothill, N; Vallage, B; Vallania, P; van Eldik, C; van Scherpenberg, J; Vandenbroucke, J; Acosta, MV; Vecchi, M; Vercellone, S; Verna, G; Viana, A; Vignatti, J; Vitale, V; Vodeb, V; Vorobiov, S; Vuillaume, T; Wagner, SJ; Walter, R; White, M; Wierzcholska, A; Will, M; Williams, D; Yang, L; Yoshida, T; Yoshikoshi, T; Zaharijas, G; Zampieri, L; Zavrtanik, D; Zavrtanik, M; Zhdanov, VI; Zivec, M

ASTROPARTICLE PHYSICS Vol. 150 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Astroparticle Physics

The local Cosmic Ray (CR) energy spectrum exhibits a spectral softening at energies around 3 PeV. Sources which are capable of accelerating hadrons to such energies are called hadronic PeVatrons. However, hadronic PeVatrons have not yet been firmly identified within the Galaxy. Several source classes, including Galactic Supernova Remnants (SNRs), have been proposed as PeVatron candidates. The potential to search for hadronic PeVatrons with the Cherenkov Telescope Array (CTA) is assessed. The focus is on the usage of very high energy γ-ray spectral signatures for the identification of PeVatrons. Assuming that SNRs can accelerate CRs up to knee energies, the number of Galactic SNRs which can be identified as PeVatrons with CTA is estimated within a model for the evolution of SNRs. Additionally, the potential of a follow-up observation strategy under moonlight conditions for PeVatron searches is investigated. Statistical methods for the identification of PeVatrons are introduced, and realistic Monte-Carlo simulations of the response of the CTA observatory to the emission spectra from hadronic PeVatrons are performed. Based on simulations of a simplified model for the evolution for SNRs, the detection of a γ-ray signal from in average 9 Galactic PeVatron SNRs is expected to result from the scan of the Galactic plane with CTA after 10 h of exposure. CTA is also shown to have excellent potential to confirm these sources as PeVatrons in deep observations with O(100) hours of exposure per source.

DOI： 10.1016/j.astropartphys.2023.102850

Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud

Acharyya, A; Adam, R; Aguasca-Cabot, A; Agudo, I; Aguirre-Santaella, A; Alfaro, J; Aloisio, R; Batista, RA; Amato, E; Angüner, EO; Aramo, C; Arcaro, C; Asano, K; Aschersleben, J; Ashkar, H; Backes, M; Baktash, A; Balazs, C; Balbo, M; Ballet, J; Bamba, A; Larriva, AB; Martins, VB; de Almeida, UB; Barrio, JA; Bastieri, D; Batista, P; Batkovic, I; Baxter, JR; Gonzalez, JB; Tjus, JB; Benbow, W; Bernardini, E; Martín, MIB; Medrano, JB; Berti, A; Bertucci, B; Beshley, V; Bhattacharjee, P; Bhattacharyya, S; Bigongiari, C; Biland, A; Bissaldi, E; Bocchino, F; Bordas, P; Borkowski, J; Bottacini, E; Böttcher, M; Bradascio, F; Brown, AM; Bulgarelli, A; Burmistrov, L; Caroff, S; Carosi, A; Carquín, E; Casanova, S; Cascone, E; Cassol, F; Cerruti, M; Chadwick, P; Chaty, S; Chen, A; Chiavassa, A; Chytka, L; Conforti, V; Cortina, J; Costa, A; Costantini, H; Cotter, G; Crestan, S; Cristofari, P; D'Ammando, F; Dalchenko, M; Dazzi, F; De Angelis, A; De Caprio, V; Dal Pino, EMD; De Martino, D; de Naurois, M; de Souza, V; del Valle, MV; Giler, AGD; Delgado, C; della Volpe, D; Depaoli, D; Di Girolamo, T; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Diebold, S; Doro, M; Dumora, D; Dwarkadas, VV; Eckner, C; Egberts, K; Emery, G; Escudero, J; Falceta-Goncalves, D; Fedorova, E; Fegan, S; Feng, Q; Ferenc, D; Ferrand, G; Fiandrini, E; Filipovic, M; Fioretti, V; Foffano, L; Fontaine, G; Fukui, Y; Gaggero, D; Galanti, G; Galaz, G; Gallozzi, S; Gammaldi, V; Garczarczyk, M; Gasbarra, C; Gasparrini, D; Ghalumyan, A; Giarrusso, M; Giavitto, G; Giglietto, N; Giordano, F; Giuliani, A; Glicenstein, JF; Goldoni, P; Coelho, JG; Granot, J; Green, D; Green, JG; Grondin, MH; Gueta, O; Hadasch, D; Hamal, P; Hassan, T; Hayashi, K; Heller, M; Cadena, SH; Hiroshima, N; Hnatyk, B; Hnatyk, R; Hofmann, W; Holder, J; Holler, M; Horan, D; Horvath, P; Hrabovsky, M; Hütten, M; Iarlori, M; Inada, T; Incardona, F; Inoue, S; Iocco, F; Jamrozy, M; Jin, W; Jung-Richardt, I; Jurysek, J; Kantzas, D; Karas, V; Katagiri, H; Kerszberg, D; Knödlseder, J; Komin, N; Kornecki, P; Kosack, K; Kowal, G; Kubo, H; Lamastra, A; Lapington, J; Lemoine-Goumard, M; Lenain, JP; Leone, F; Leto, G; Leuschner, F; Lindfors, E; Lohse, T; Lombardi, S; Longo, F; López-Coto, R; López-Oramas, A; Loporchio, S; Luque-Escamilla, PL; Macias, O; Majumdar, P; Mandat, D; Mangano, S; Manicò, G; Mariotti, M; Marquez, P; Marsella, G; Martí, J; Martin, P; Martínez, M; Mazin, D; Menchiari, S; Meyer, DMA; Miceli, D; Miceli, M; Michalowski, J; Mitchell, A; Moderski, R; Mohrmann, L; Molero, M; Molina, E; Montaruli, T; Moralejo, A; Morcuende, D; Morselli, A; Moulin, E; Moya, V; Mukherjee, R; Munari, K; Muraczewski, A; Nagataki, S; Nakamori, T; Nayak, A; Niemiec, J; Nievas, M; Nikolajuk, M; Nishijima, K; Noda, K; Nosek, D; Novosyadlyj, B; Nozaki, S; Ohishi, M; Ohm, S; Okumura, A; Olmi, B; Ong, RA; Orienti, M; Orito, R; Orlandini, M; Orlando, E; Orlando, S; Ostrowski, M; Oya, I; Pagliaro, A; Palatka, M; Pantaleo, FR; Paoletti, R; Paredes, JM; Parmiggiani, N; Patricelli, B; Pech, M; Pecimotika, M; Persic, M; Petruk, O; Pierre, E; Pietropaolo, E; Pirola, G; Pohl, M; Prandini, E; Priyadarshi, C; Pühlhofer, G; Pumo, ML; Punch, M; Queiroz, FS; Quirrenbach, A; Rainò, S; Rando, R; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ribó, M; Richtler, T; Rico, J; Rieger, F; Rigoselli, M; Rizi, V; Roache, E; Fernandez, GR; Romano, P; Romeo, G; Rosado, J; de Leon, AR; Rudak, B; Rulten, C; Sadeh, I; Saito, T; Sanchez-Conde, M; Sano, H; Santangelo, A; Santos-Lima, R; Sarkar, S; Saturni, FG; Scherer, A; Schovanek, P; Schussler, F; Schwanke, U; Sergijenko, O; Servillat, M; Siejkowski, H; Siqueira, C; Spencer, S; Stamerra, A; Stanic, S; Steppa, C; Stolarczyk, T; Suda, Y; Tavernier, T; Teshima, M; Tibaldo, L; Torres, DF; Tothill, N; Vacula, M; Vallage, B; Vallania, P; van Eldik, C; Acosta, MV; Vecchi, M; Ventura, S; Vercellone, S; Viana, A; Vigorito, CF; Vink, J; Vitale, V; Vodeb, V; Vorobiov, S; Vuillaume, T; Wagner, SJ; Walter, R; White, M; Wierzcholska, A; Will, M; Yamazaki, R; Yang, L; Yoshikoshi, T; Zacharias, M; Zaharijas, G; Zavrtanik, D; Zavrtanik, M; Zdziarski, AA; Zhdanov, VI; Zietara, K; Zivec, M

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 523 ( 4 ) page： 5353 - 5387 2023.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Monthly Notices of the Royal Astronomical Society

A deep survey of the Large Magellanic Cloud at ∼0.1-100 TeV photon energies with the Cherenkov Telescope Array is planned. We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters, mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3-2.4 pending a flux increase by a factor of >3-4 over ∼2015-2035. Large-scale interstellar emission remains mostly out of reach of the survey if its >10 GeV spectrum has a soft photon index ∼2.7, but degree-scale 0.1-10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1−10 per cent of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within <100 pc. Finally, the survey could probe the canonical velocity-averaged cross-section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles.

DOI： 10.1093/mnras/stad1576

Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

Abé, H; Abé, S; Acciari, VA; Agudo, I; Aniello, T; Ansoldi, S; Antonelli, LA; Arbet-Engels, A; Arcaro, C; Artero, M; Asano, K; Baack, D; Babic, A; Baquero, A; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bednarek, W; Bernardini, E; Bernardos, M; Berti, A; Besenrieder, J; Bhattacharyya, W; Bigongiari, C; Biland, A; Blanch, O; Bonnoli, G; Bosnjak, Z; Burelli, I; Busetto, G; Carosi, R; Carretero-Castrillo, M; Castro-Tirado, AJ; Ceribella, G; Chai, Y; Chilingarian, A; Cikota, S; Colombo, E; Contreras, JL; Cortina, J; Covino, S; D'Amico, G; D'Elia, V; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Del Popolo, A; Delfino, M; Delgado, J; Mendez, CD; Depaoli, D; Di Pierro, F; Di Venere, L; Espiñeira, EDS; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsaesser, D; Emery, G; Escudero, J; Ramazani, VF; Fariña, L; Fattorini, A; Foffano, L; Font, L; Fruck, C; Fukami, S; Fukazawa, Y; López, RJG; Garczarczyk, M; Gasparyan, S; Gaug, M; Paiva, JGG; Giglietto, N; Giordano, F; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, JG; Hadasch, D; Hahn, A; Hassan, T; Heckmann, L; Herrera, J; Hrupec, D; Hütten, M; Imazawa, R; Inada, T; Iotov, R; Ishio, K; Martínez, IJ; Jormanainen, J; Kerszberg, D; Kobayashi, Y; Kubo, H; Kushida, J; Lamastra, A; Lelas, D; Leone, F; Lindfors, E; Linhoff, L; Lombardi, S; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Lyard, E; Fraga, BMD; Majumdar, P; Makariev, M; Maneva, G; Mang, N; Manganaro, M; Mangano, S; Mannheim, K; Mariotti, M; Martínez, M; Mas-Aguilar, A; Mazin, D; Menchiari, S; Mender, S; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Molina, E; Mondal, HA; Moralejo, A; Morcuende, D; Moreno, V; Nakamori, T; Nanci, C; Nava, L; Neustroev, V; Rosillo, MN; Nigro, C; Nilsson, K; Nishijima, K; Ekoume, TN; Noda, K; Nozaki, S; Ohtani, Y; Oka, T; Okumura, A; Otero-Santos, J; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, JM; Pavletic, L; Persic, M; Pihet, M; Pirola, G; Podobnik, F; Moroni, PGP; Prandini, E; Principe, G; Priyadarshi, C; Rhode, W; Ribó, M; Rico, J; Righi, C; Rugliancich, A; Sahakyan, N; Saito, T; Sakurai, S; Satalecka, K; Saturni, FG; Schleicher, B; Schmidt, K; Schmuckermaier, F; Schubert, JL; Schweizer, T; Sitarek, J; Sliusar, V; Sobczynska, D; Spolon, A; Stamerra, A; Striskovic, J; Strom, D; Strzys, M; Suda, Y; Suric, T; Tajima, H; Takahashi, M; Takeishi, R; Tavecchio, F; Temnikov, P; Terauchi, K; Terzic, T; Teshima, M; Tosti, L; Truzzi, S; Tutone, A; Ubach, S; van Scherpenberg, J; Acosta, MV; Ventura, S; Verguilov, V; Viale, I; Vigorito, CF; Vitale, V; Vovk, I; Walter, R; Will, M; Wunderlich, C; Yamamoto, T; Zaric, D; Cerruti, M; Acosta-Pulido, JA; Apolonio, G; Bachev, R; Balokovic, M; Benítez, E; Björklund, I; Bozhilov, V; Brown, LF; Bugg, A; Carbonell, W; Carnerero, MI; Carosati, D; Casadio, C; Chamani, W; Chen, WP; Chigladze, RA; Damljanovic, G; Epps, K; Erkenov, A; Feige, M; Finke, J; Fuentes, A; Gazeas, K; Giroletti, M; Grishina, TS; Gupta, AC; Gurwell, MA; Heidemann, E; Hiriart, D; Hou, WJ; Hovatta, T; Ibryamov, S; Joner, MD; Jorstad, SG; Kania, J; Kiehlmann, S; Kimeridze, GN; Kopatskaya, EN; Kopp, M; Korte, M; Kotas, B; Koyama, S; Kramer, JA; Kunkel, L; Kurtanidze, SO; Kurtanidze, OM; Lähteenmäki, A; López, JM; Larionov, VM; Larionova, EG; Larionova, LV; Leto, C; Lorey, C; Mújica, R; Madejski, GM; Marchili, N; Marscher, AP; Minev, M; Modaressi, A; Morozova, DA; Mufakharov, T; Myserlis, I; Nikiforova, AA; Nikolashvili, MG; Ovcharov, E; Perri, M; Raiteri, CM; Readhead, ACS; Reimer, A; Reinhart, D; Righini, S; Rosenlehner, K; Sadun, AC; Savchenko, SS; Scherbantin, A; Schneider, L; Schoch, K; Seifert, D; Semkov, E; Sigua, LA; Singh, C; Sola, P; Sotnikova, Y; Spencer, M; Steineke, R; Stojanovic, M; Strigachev, A; Tornikoski, M; Traianou, E; Tramacere, A; Troitskaya, YV; Troitskiy, IS; Trump, JB; Tsai, A; Valcheva, A; Vasilyev, AA; Verrecchia, F; Villata, M; Vince, O; Vrontaki, K; Weaver, ZR; Zaharieva, E; Zottmann, N

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES Vol. 266 ( 2 ) 2023.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal, Supplement Series

We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) 3-rays. A significant correlation (>3σ) between X-rays and VHE 3-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy 3-rays and radio, with the radio lagging by more than 100 days, placing the 3-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE 3-rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock.

DOI： 10.3847/1538-4365/acc181

Multiwavelength study of the galactic PeVatron candidate LHAASO J2108+5157

Abe, S; Aguasca-Cabot, A; Agudo, I; Crespo, NA; Antonelli, LA; Aramo, C; Arbet-Engels, A; Artero, M; Asano, K; Aubert, P; Baktash, A; Bamba, A; Larriva, AB; Baroncelli, L; de Almeida, UB; Barrio, JA; Batkovic, I; Baxter, J; González, JB; Bernardini, E; Bernardos, MI; Medrano, JB; Berti, A; Bhattacharjee, P; Biederbeck, N; Bigongiari, C; Bissaldi, E; Blanch, O; Bordas, P; Buisson, C; Bulgarelli, A; Burelli, I; Buscemi, M; Cardillo, M; Caroff, S; Carosi, A; Cassol, F; Cauz, D; Ceribella, G; Chai, Y; Cheng, K; Chiavassa, A; Chikawa, M; Chytka, L; Cifuentes, A; Contreras, JL; Cortina, J; Costantini, H; D'Amico, G; Dalchenko, M; De Angelis, A; de Lavergne, MD; De Lotto, B; de Menezes, R; Deleglise, G; Delgado, C; Mengual, JD; della Volpe, D; Dellaiera, M; Di Piano, A; Di Pierro, F; Di Tria, R; Di Venere, L; Díaz, C; Dominik, RM; Prester, DD; Donini, A; Dorner, D; Doro, M; Elsässer, D; Emery, G; Escudero, J; Ramazani, VF; Ferrara, G; Fiasson, A; Coromina, LF; Fröse, S; Fukami, S; Fukazawa, Y; Garcia, E; López, RG; Gasparrini, D; Geyer, D; Paiva, JG; Giglietto, N; Giordano, F; Giro, E; Gliwny, P; Godinovic, N; Grau, R; Green, D; Green, J; Gunji, S; Hackfeld, J; Hadasch, D; Hahn, A; Hashiyama, K; Hassan, T; Hayashi, K; Heckmann, L; Heller, M; Llorente, JH; Hirotani, K; Hoffmann, D; Horns, D; Houles, J; Hrabovsky, M; Hrupec, D; Hui, D; Hütten, M; Imazawa, R; Inada, T; Inome, Y; Ioka, K; Iori, M; Ishio, K; Iwamura, Y; Jacquemont, M; Martinez, IJ; Jurysek, J; Kagaya, M; Karas, V; Katagiri, H; Kataoka, J; Kerszberg, D; Kobayashi, Y; Kong, A; Kubo, H; Kushida, J; Lainez, M; Lamanna, G; Lamastra, A; Le Flour, T; Linhoff, M; Longo, F; López-Coto, R; López-Moya, M; López-Oramas, A; Loporchio, S; Lorini, A; Luque-Escamilla, PL; Majumdar, P; Makariev, M; Mandat, D; Manganaro, M; Manicò, G; Mannheim, K; Mariotti, M; Marquez, P; Marsella, G; Martí, J; Martinez, O; Martínez, G; Martínez, M; Marusevec, P; Mas-Aguilar, A; Maurin, G; Mazin, D; Guillen, EM; Micanovic, S; Miceli, D; Miener, T; Miranda, JM; Mirzoyan, R; Mizuno, T; Gonzalez, MM; Molina, E; Montaruli, T; Monteiro, I; Moralejo, A; Morcuende, D; Morselli, A; Mrakovcic, K; Murase, K; Nagai, A; Nakamori, T; Nickel, L; Nievas, M; Nishijima, K; Noda, K; Nosek, D; Nozaki, S; Ohishi, M; Ohtani, Y; Okazaki, N; Okumura, A; Orito, R; Otero-Santos, J; Palatiello, M; Paneque, D; Pantaleo, FR; Paoletti, R; Paredes, JM; Pavletic, L; Pech, M; Pecimotika, M; Pietropaolo, E; Pirola, G; Podobnik, F; Poireau, V; Polo, M; Pons, E; Prandini, E; Prast, J; Priyadarshi, C; Prouza, M; Rando, R; Rhode, W; Ribó, M; Rizi, V; Fernandez, GR; Saito, T; Sakurai, S; Sanchez, DA; Saric, T; Saturni, FG; Scherpenberg, J; Schleicher, B; Schmuckermaier, F; Schubert, JL; Schussler, F; Schweizer, T; Arroyo, MS; Sitarek, J; Sliusar, V; Spolon, A; Striskovic, J; Strzys, M; Suda, Y; Sunada, Y; Tajima, H; Takahashi, M; Takahashi, H; Takata, J; Takeishi, R; Tam, PHT; Tanaka, SJ; Tateishi, D; Temnikov, P; Terada, Y; Terauchi, K; Terzic, T; Teshima, M; Tluczykont, M; Tokanai, F; Torres, DF; Travnicek, P; Truzzi, S; Tutone, A; Uhlrich, G; Vacula, M; Acosta, MV; Verguilov, V; Viale, I; Vigliano, A; Vigorito, CF; Vitale, V; Voutsinas, G; Vovk, I; Vuillaume, T; Walter, R; Will, M; Yamamoto, T; Yamazaki, R; Yoshida, T; Yoshikoshi, T; Zywucka, N; Balbo, M; Eckert, D; Tramacere, A

ASTRONOMY & ASTROPHYSICS Vol. 673 2023.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. Several new ultrahigh-energy (UHE) γ-ray sources have recently been discovered by the Large High Altitude Air Shower Observatory (LHAASO) collaboration. These represent a step forward in the search for the so-called Galactic PeVatrons, the enigmatic sources of the Galactic cosmic rays up to PeV energies. However, it has been shown that multi-TeV γ-ray emission does not necessarily prove the existence of a hadronic accelerator in the source; indeed this emission could also be explained as inverse Compton scattering from electrons in a radiation-dominated environment. A clear distinction between the two major emission mechanisms would only be made possible by taking into account multi-wavelength data and detailed morphology of the source. Aims. We aim to understand the nature of the unidentified source LHAASO J2108+5157, which is one of the few known UHE sources with no very high-energy (VHE) counterpart. Methods. We observed LHAASO J2108+5157 in the X-ray band with XMM-Newton in 2021 for a total of 3.8 hours and at TeV energies with the Large-Sized Telescope prototype (LST-1), yielding 49 hours of good-quality data. In addition, we analyzed 12 years of Fermi-LAT data, to better constrain emission of its high-energy (HE) counterpart 4FGL J2108.0+5155. We used naima and jetset software packages to examine the leptonic and hadronic scenario of the multi-wavelength emission of the source. Results. We found an excess (3.7σ) in the LST-1 data at energies E > 3 TeV. Further analysis of the whole LST-1 energy range, assuming a point-like source, resulted in a hint (2.2σ) of hard emission, which can be described with a single power law with a photon index of Σ = 1.6 ± 0.2 the range of 0.3 - 100 TeV. We did not find any significant extended emission that could be related to a supernova remnant (SNR) or pulsar wind nebula (PWN) in the XMM-Newton data, which puts strong constraints on possible synchrotron emission of relativistic electrons. We revealed a new potential hard source in Fermi-LAT data with a significance of 4σ and a photon index of Σ = 1.9 ± 0.2, which is not spatially correlated with LHAASO J2108+5157, but including it in the source model we were able to improve spectral representation of the HE counterpart 4FGL J2108.0+5155. Conclusions. The LST-1 and LHAASO observations can be explained as inverse Compton-dominated leptonic emission of relativistic electrons with a cutoff energy of 100-30+70 TeV. The low magnetic field in the source imposed by the X-ray upper limits on synchrotron emission is compatible with a hypothesis of a PWN or a TeV halo. Furthermore, the spectral properties of the HE counterpart are consistent with a Geminga-like pulsar, which would be able to power the VHE-UHE emission. Nevertheless, the lack of a pulsar in the neighborhood of the UHE source is a challenge to the PWN/TeV-halo scenario. The UHE γ rays can also be explained as π0 decay-dominated hadronic emission due to interaction of relativistic protons with one of the two known molecular clouds in the direction of the source. Indeed, the hard spectrum in the LST-1 band is compatible with protons escaping a shock around a middle-aged SNR because of their high low-energy cut-off, but the origin of the HE γ-ray emission remains an open question.

DOI： 10.1051/0004-6361/202245086

MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7

Abe H., Abe S., Acciari V.A., Agudo I., Aniello T., Ansoldi S., Antonelli L.A., Arbet Engels A., Arcaro C., Artero M., Asano K., Baack D., Babić A., Baquero A., Barres De Almeida U., Barrio J.A., Batković I., Baxter J., Becerra González J., Bednarek W., Bernardini E., Bernardos M., Berti A., Besenrieder J., Bhattacharyya W., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bošnjak , Burelli I., Busetto G., Carosi R., Carretero-Castrillo M., Castro-Tirado A.J., Ceribella G., Chai Y., Chilingarian A., Cikota S., Colombo E., Contreras J.L., Cortina J., Covino S., D'Amico G., D'Elia V., Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Delgado Mendez C., Depaoli D., Di Pierro F., Di Venere L., Do Souto Espiñeira E., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Escudero J., Fallah Ramazani V., Fariña L., Fattorini A., Font L., Fruck C., Fukami S., Fukazawa Y., García López R.J., Garczarczyk M., Gasparyan S., Gaug M., Giesbrecht Paiva J.G., Giglietto N., Giordano F., Gliwny P., Godinović N., Grau R., Green D., Green J.G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hrupec D., Hütten M., Imazawa R., Inada T., Iotov R., Ishio K., Jiménez Martínez I., Jormanainen J., Kerszberg D., Kobayashi Y., Kubo H., Kushida J.

Astronomy and Astrophysics Vol. 671 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics

Context. Certain types of supernova remnants (SNRs) in our Galaxy are assumed to be PeVatrons, capable of accelerating cosmic rays (CRs) to ∼ PeV energies. However, conclusive observational evidence for this has not yet been found. The SNR G106.3+2.7, detected at 1- 100 TeV energies by different γ-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape, which can be divided into a head and a tail region with different physical conditions. However, in which region the 100 TeV emission is produced has not yet been identified because of the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear as to whether the origin of the γ-ray emission is leptonic or hadronic. Aims. With the better angular resolution provided by new MAGIC data compared to earlier γ-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1 resolution at TeV energies. Methods. We observed the SNR G106.3+2.7 using the MAGIC telescopes for 121.7 h in total - after quality cuts - between May 2017 and August 2019. The analysis energy threshold is ∼0.2 TeV, and the angular resolution is 0.07-0.1. We examined the γ-ray spectra of different parts of the emission, whilst benefitting from the unprecedented statistics and angular resolution at these energies provided by our new data. We also used measurements at other wavelengths such as radio, X-rays, GeV γ-rays, and 10 TeV γ-rays to model the emission mechanism precisely. Results. We detect extended γ-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detect a significant γ-ray emission with energies above 6.0 TeV from only the tail region suggests that the emissions above 10 TeV detected with air shower experiments (Milagro, HAWC, Tibet ASγ and LHAASO) are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of ∼1 PeV for that region. Such high-energy emission in this middle-aged SNR (4-10 kyr) can be explained by considering a scenario where protons escaping from the SNR in the past interact with surrounding dense gases at present. Conclusions. The γ-ray emission region detected with the MAGIC telescopes in the SNR G106.3+2.7 is extended and spatially coincident with the radio continuum morphology. The multi-wavelength spectrum of the emission from the tail region suggests proton acceleration up to ∼PeV, while the emission mechanism of the head region could either be hadronic or leptonic.

DOI： 10.1051/0004-6361/202244931

Gamma-ray observations of MAXI J1820+070 during the 2018 outburst

Abe H., Abe S., Acciari V. A., Aniello T., Ansoldi S., Antonelli L. A., Engels A. Arbet, Arcaro C., Artero M., Asano K., Baack D., Babic A., Baquero A., de Almeida U. Barres, Barrio J. A., Batkovic I, Baxter J., Gonzalez J. Becerra, Bednarek W., Bernardini E., Bernardos M., Berti A., Besenrieder J., Bhattacharyya W., Bigongiari C., Biland A., Blanch O., Bonnoli G., Bosnjak Z., Burelli I, Busetto G., Carosi R., Carretero-Castrillo M., Ceribella G., Chai Y., Chilingarian A., Cikota S., Colombo E., Contreras J. L., Cortina J., Covino S., D'Amico G., D'Elia V, Da Vela P., Dazzi F., De Angelis A., De Lotto B., Del Popolo A., Delfino M., Delgado J., Mendez C. Delgado, Depaoli D., Di Pierro F., Di Venere L., Prester D. Dominis, Donini A., Dorner D., Doro M., Elsaesser D., Emery G., Ramazani V. Fallah, Farina L., Fattorini A., Font L., Fruck C., Fukami S., Fukazawa Y., Lopez R. J. Garcia, Garczarczyk M., Gasparyan S., Gaug M., Paiva J. G. Giesbrecht, Giglietto N., Giordano F., Gliwny P., Godinovic N., Grau R., Green D., Green J. G., Hadasch D., Hahn A., Hassan T., Heckmann L., Herrera J., Hoang J., Hrupec D., Hutten M., Imazawa R., Inada T., Iotov R., Ishio K., Martinez I. Jimenez, Jormanainen J., Kerszberg D., Kobayashi Y., Kubo H., Kushida J., Lamastra A., Lelas D., Leone F., Lindfors E., Linhoff L., Lombardi S., Longo F., Lopez-Coto R., Lopez-Moya M., Lopez-Oramas A., Loporchio S., Lorini A., Lyard E., Fraga B. Machado de Oliveira, Majumdar P., Makariev M., Maneva G., Mang N., Manganaro M., Mangano S., Mannheim K., Mariotti M., Martinez M., Aguilar A. Mas, Mazin D., Menchiari S., Mender S., Micanovic S., Miceli D., Miener T., Miranda J. M., Mirzoyan R., Molina E., Mondal H. A., Moralejo A., Morcuende D., Moreno V, Nakamori T., Nanci C., Nava L., Neustroev V, Rosillo M. Nievas, Nigro C., Nilsson K., Nishijima K., Ekoume T. Njoh, Noda K., Nozaki S., Ohtani Y., Oka T., Okumura A., Otero-Santos J., Paiano S., Palatiello M., Paneque D., Paoletti R., Paredes J. M., Pavletic L., Persic M., Pihet M., Pirola G., Podobnik F., Moroni P. G. Prada, Prandini E., Principe G., Priyadarshi C., Puljak I, Rhode W., Ribo M., Rico J., Righi C., Rugliancich A., Sahakyan N., Saito T., Sakurai S., Satalecka K., Saturni F. G., Schleicher B., Schmidt K., Schmuckermaier F., Schubert J. L., Schweizer T., Sitarek J., Sliusar V, Sobczynska D., Spolon A., Stamerra A., Striskovic J., Strom D., Strzys M., Suda Y., Suric T., Tajima H., Takahashi M., Takeishi R., Tavecchio F., Temnikov P., Terauchi K., Terzic T., Teshima M., Tosti L., Truzzi S., Tutone A., Ubach S., van Scherpenberg J., Acosta M. Vazquez, Ventura S., Verguilov V., Viale I, Vigorito C. F., Vitale V., Vovk I, Walter R., Will M., Wunderlich C., Yamamoto T., Zaric D., Abdalla H., Aharonian F., Benkhali F. Ait, Anguner E. O., Ashkar H., Backes M., Baghmanyan V, Martins V. Barbosa, Batzofin R., Becherini Y., Berge D., Bernloehr K., Bottcher M., Boisson C., Bolmont J., de Lavergne M. de Bony, Bradascio F., Breuhaus M., Brose R., Brun F., Bulik T., Bylund T., Cangemi F., Caroff S., Casanova S., Cerruti M., Chand T., Chandra S., Chen A., Chibueze O. U., Cotter G., Cristofari P., Mbarubucyeye J. Damascene, Devin J., Djannati-Atai A., Dmytriiev A., Egberts K., Ernenwein J-P, Fiasson A., de Clairfontaine G. Fichet, Fontaine G., Fuessling M., Funk S., Gabici S., Ghafourizadeh S., Giavitto G., Glawion D., Glicenstein J. F., Goswami P., Grolleron G., Hinton J. A., Horbe M., Hoischen C., Holch T. L., Holler M., Horns D., Huang Zhiqiu, Jamrozy M., Jankowsky F., Joshi V, Jung-Richardt I, Kasai E., Katarzynski K., Katz U., Khelifi B., Kluzniak W., Komin Nu, Kosack K., Kostunin D., Lang R. G., Le Stum S., Lemiere A., Lemoine-Goumard M., Lenain J-P, Leuschner F., Lohse T., Luashvili A., Lypova I, Mackey J., Majumdar J., Malyshev D., Malyshev D., Marandon V, Marchegiani P., Marti-Devesa G., Marx R., Maurin G., Meyer M., Mitchell A., Moderski R., Mohrmann L., Montanari A., Moulin E., Muller J., Murach T., Nakashima K., de Naurois M., Nayerhoda A., Niemiec J., Noel A. Pniyana, O'Brien P., Ohm S., Olivera-Nieto L., Wilhelmi E. de Ona, Ostrowski M., Panny S., Panter M., Parsons R. D., Poireau V, Prokhorov D. A., Prokoph H., Puehlhofer G., Punch M., Quirrenbach A., Reichherzer P., Reimer A., Reimer O., Renaud M., Rieger F., Rowell G., Rudak B., Ricarte H. Rueda, Ruiz-Velasco E., Sahakian V, Salzmann H., Santangelo A., Sasaki M., Schaefer J., Schussler F., Schutte H. M., Schwanke U., Shapopi J. N. S., Sol H., Specovius A., Spencer S., Stawarz L., Steenkamp R., Steinmassl S., Steppa C., Sushch I, Suzuki H., Takahashi T., Tanaka T., Thorpe-Morgan C., Tluczykont M., Tomankova L., Tsuji N., Uchiyama Y., van Eldik C., van Soelen B., Vecchi M., Veh J., Venter C., Vink J., Wagner S. J., White R., Wierzcholska A., Wong Yu Wun, Yusafzai A., Zacharias M., Zanin R., Zargaryan D., Zdziarski A. A., Zech A., Zhu S. J., Zouari S., Zywucka N., Acharyya A., Adams C. B., Batista P., Benbow W., Capasso M., Christiansen J. L., Chromey A. J., Errando M., Falcone A., Feng Q., Finley J. P., Foote G. M., Fortson L., Furniss A., Gent A., Hanlon W. E., Hervet O., Holder J., Hona B., Humensky T. B., Jin W., Kaaret P., Kertzman M., Kherlakian M., Kleiner T. K., Kumar S., Lang M. J., Lundy M., Maier G., McGrath C. E., Millis J., Moriarty P., Mukherjee R., O'Brien S., Ong R. A., Park N., Patel S. R., Pfrang K., Pohl M., Pueschel E., Quinn J., Ragan K., Reynolds P. T., Ribeiro D., Roache E., Ryan J. L., Sadeh I, Saha L., Santander M., Sembroski G. H., Shang R., Splettstoesser M., Tak D., Tucci J. V, Weinstein A., Williams D. A., Williamson T. J., Bosch-Ramon V, Celma C., Linares M., Russell D. M., Sala G.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 517 ( 4 ) page： 4736 - 4751 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Monthly Notices of the Royal Astronomical Society

MAXI J1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to ∼500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 1011 and 1013 cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.

DOI： 10.1093/mnras/stac2686

Active Galactic Nuclei population studies with the Cherenkov Telescope Array

Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E., Bernardos M.I., Bernlöhr K., Berti A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) observatory is the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Building on the strengths of current IACTs, CTA is designed to achieve an order of magnitude improvement in sensitivity, with unprecedented angular and energy resolution. CTA will also increase the energy reach of IACTs, observing photons in the energy range from 20 GeV to beyond 100 TeV. These advances in performance will see CTA heralding in a new era for high-energy astrophysics, with the emphasis shifting from source discovery, to population studies and precision measurements. In this talk we discuss CTA’s ability to conduct source population studies of γ-ray bright active galactic nuclei and how this ability will enhance our understanding on the redshift evolution of this dominant γ-ray source class.

The Small-Sized Telescopes for the Southern Site of the Cherenkov Telescope Array

Amans J.P., Berge D., Bonanno G., Bose R.B., Brown A.M., Buckley J.H., Chadwick P.M., Conte F., Cotter G., De Frondat F., De Simone N., Dournaux J.L., Duffy C.A., Einecke S., Fasola G., Funk S., Giavitto G., Hinton J.A., Huet J.M., La Palombara N., Lapington J.S., Laporte P., Leach S.A., Leto G., Lloyd S., Lombardi S., Nayak A., Okumura A., Pareschi G., Prokoph H., Rébert E., Ross D., Rowell G., Scuderi S., Sol H., Spencer S., Tajima H., Trois A., Vercellone S., Vink J., Watson J.J., White R., Zech A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will use three telescope sizes to efficiently detect cosmic gamma rays in the energy range from several tens of GeV to hundreds of TeV. The Small-Sized Telescopes (SSTs) will form the largest section of the array, covering an area of many square kilometres on the CTA southern site in Paranal, Chile. Up to 70 SSTs will be implemented by an international consortium of institutes and teams as an in-kind contribution to the CTA Observatory. The SSTs will provide unprecedented sensitivity to gamma rays above 1 TeV and the highest angular resolution of any instrument above the hard X-ray band. CTA has recently finalised the technology that will be used for the SSTs: the telescopes will be a dual-reflector design with a primary reflector of 4 m diameter, equipped with an SiPM-based camera with full waveform readout from ∼2000 channels covering a ∼9° field of view. The Schwarzschild-Couder optical configuration leads to a small plate-scale, and consequently a compact, cost-efficient camera. In this contribution, we describe the experience gained operating telescope and camera prototypes during the CTA preparatory phase, and the development of the final SST design.

The Cherenkov Telescope Array: layout, design and performance

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next generation very-high-energy gamma-ray observatory. CTA is expected to provide substantial improvement in accuracy and sensitivity with respect to existing instruments thanks to a tenfold increase in the number of telescopes and their state-of-the-art design. Detailed Monte Carlo simulations are used to further optimise the number of telescopes and the array layout, and to estimate the observatory performance using updated models of the selected telescope designs. These studies are presented in this contribution for the two CTA stations located on the island of La Palma (Spain) and near Paranal (Chile) and for different operation and observation conditions.

The Cherenkov Telescope Array transient and multi-messenger program

Carosi A., López-Oramas A., Longo F., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is a next generation ground-based very-high-energy gamma-ray observatory that will allow for observations in the >10 GeV range with unprecedented photon statistics and sensitivity. This will enable the investigation of the yet-marginally explored physics of short-time-scale transient events. CTA will thus become an invaluable instrument for the study of the physics of the most extreme and violent objects and their interactions with the surrounding environment. The CTA Transient program includes follow-up observations of a wide range of multi-wavelength and multi-messenger alerts, ranging from compact galactic binary systems to extragalactic events such as gamma-ray bursts (GRBs), core-collapse supernovae and bright AGN flares. In recent years, the first firm detection of GRBs by current Cherenkov telescope collaborations, the proven connection between gravitational waves and short GRBs, as well as the possible neutrino-blazar association with TXS 0506+056 have shown the importance of coordinated follow-up observations triggered by these different cosmic signals in the framework of the birth of multi-messenger astrophysics. In the next years, CTA will play a major role in these types of observations by taking advantage of its fast slewing (especially for the CTA Large Size Telescopes), large effective area and good sensitivity, opening new opportunities for time-domain astrophysics in an energy range not affected by selective absorption processes typical of other wavelengths. In this contribution we highlight the common approach adopted by the CTA Transients physics working group to perform the study of transient sources in the very-high-energy regime.

Status and results of the prototype LST of CTA

Mazin D., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T., Inome Y., Iori M., Ishio K., Iwamura Y., Jacquemont M., Jimenez Martinez I., Jouvin L.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Large-Sized Telescopes (LSTs) of Cherenkov Telescope Array (CTA) are designed for gamma-ray studies focusing on low energy threshold, high flux sensitivity, rapid telescope repositioning speed and a large field of view. Once the CTA array is complete, the LSTs will be dominating the CTA performance between 20 GeV and 150 GeV. During most of the CTA Observatory construction phase, however, the LSTs will be dominating the array performance until several TeVs. In this presentation we will report on the status of the LST-1 telescope inaugurated in La Palma, Canary islands, Spain in 2018. We will show the progress of the telescope commissioning, compare the expectations with the achieved performance, and give a glance of the first physics results.

Southern African Large Telescope Spectroscopy of BL Lacs for the CTA project

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

In the last two decades, very-high-energy gamma-ray astronomy has reached maturity: over 200 sources have been detected, both Galactic and extragalactic, by ground-based experiments. At present, Active Galactic Nuclei (AGN) make up about 40% of the more than 200 sources detected at very high energies with ground-based telescopes, the majority of which are blazars, i.e. their jets are closely aligned with the line of sight to Earth and three quarters of which are classified as high-frequency peaked BL Lac objects. One challenge to studies of the cosmological evolution of BL Lacs is the difficulty of obtaining redshifts from their nearly featureless, continuum-dominated spectra. It is expected that a significant fraction of the AGN to be detected with the future Cherenkov Telescope Array (CTA) observatory will have no spectroscopic redshifts, compromising the reliability of BL Lac population studies, particularly of their cosmic evolution. We started an effort in 2019 to measure the redshifts of a large fraction of the AGN that are likely to be detected with CTA, using the Southern African Large Telescope (SALT). In this contribution, we present two results from an on-going SALT program focused on the determination of BL Lac object redshifts that will be relevant for the CTA observatory.

Sensitivity of the Cherenkov Telescope Array to emission from the gamma-ray counterparts of neutrino events

Sergijenko O., Brown A.M., Fiorillo D.F.G., de León A.R., Satalecka K., Tung C.F., Reimann R., Glauch T., Taboada I., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

We investigate the possibility of detection of the VHE gamma-ray counterparts to the neutrino astrophysical sources within the Neutrino Target of Opportunity (NToO) program of CTA using the populations simulated by the FIRESONG software to resemble the diffuse astrophysical neutrino flux measured by IceCube. We derive the detection probability for different zenith angles and geomagnetic field configurations. The difference in detectability of sources between CTA-North and CTA-South for the average geomagnetic field is not substantial. We investigate the effect of a higher night-sky background and the preliminary CTA Alpha layout on the detection probability.

Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

High-energy gamma rays are promising tools to constrain or reveal the nature of dark matter, in particular Weakly Interacting Massive Particles. Being well into its pre-construction phase, the Cherenkov Telescope Array (CTA) will soon probe the sky in the 20 GeV - 300 TeV energy range. Thanks to its improved energy and angular resolutions as well as significantly larger effective area when compared to the current generation of Cherenkov telescopes, CTA is expected to probe heavier dark matter, with unprecedented sensitivity, reaching the thermal annihilation cross-section at 1 TeV. This talk will summarise the planned dark matter search strategies with CTA, focusing on the signal from the Galactic centre. As observed with the Fermi LAT at lower energies, this region is rather complex and CTA will be the first ground-based observatory sensitive to the large scale diffuse astrophysical emission from that region. We report on the collaboration effort to study the impact of such extended astrophysical backgrounds on the dark matter search, based on Fermi-LAT data in order to guide our observational strategies, taking into account various sources of systematic uncertainty.

Sensitivity of CTA to gamma-ray emission from the Perseus galaxy cluster

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

In these proceedings we summarize the current status of the study of the sensitivity of the Cherenkov Telescope Array (CTA) to detect diffuse gamma-ray emission from the Perseus galaxy cluster. Gamma-ray emission is expected in galaxy clusters both from interactions of cosmic rays (CR) with the intra-cluster medium, or as a product of annihilation or decay of dark matter (DM) particles in case they are weakly interactive massive particles (WIMPs). The observation of Perseus constitutes one of the Key Science Projects to be carried out by the CTA Consortium. In this contribution, we focus on the DM-induced component of the flux. Our DM modelling includes the substructures we expect in the main halo which will boost the annihilation signal significantly. We adopt an ON/OFF observation strategy and simulate the expected gamma-ray signals. Finally we compute the expected CTA sensitivity using a likelihood maximization analysis including the most recent CTA instrument response functions. In absence of signal, we show that CTA will allow us to provide stringent and competitive constraints on TeV DM, especially for the case of DM decay.

Searching for very-high-energy electromagnetic counterparts to gravitational-wave events with the Cherenkov Telescope Array

Patricelli B., Carosi A., Nava L., Seglar-Arroyo M., Schüssler F., Stamerra A., Adelfio A., Ashkar H., Bulgarelli A., Di Girolamo T., Di Piano A., Gasparetto T., Green J., Longo F., Agudo I., Berti A., Bissaldi E., Cella G., Circiello A., Covino S., Ghirlanda G., Humensky B., Inoue S., Lefaucheur J., Filipovic M., Razzano M., Ribeiro D., Sergijenko O., Stratta G., Vergani S., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The detection of electromagnetic (EM) emission following the gravitational wave (GW) event GW170817 opened the era of multi-messenger astronomy with GWs and provided the first direct evidence that at least a fraction of binary neutron star (BNS) mergers are progenitors of short Gamma-Ray Bursts (GRBs). GRBs are also expected to emit very-high energy (VHE, > 100 GeV) photons, as proven by the recent MAGIC and H.E.S.S. observations. One of the challenges for future multi-messenger observations will be the detection of such VHE emission from GRBs in association with GWs. In the next years, the Cherenkov Telescope Array (CTA) will be a key instrument for the EM follow-up of GW events in the VHE range, owing to its unprecedented sensitivity, rapid response, and capability to monitor a large sky area via scan-mode operation. We present the CTA GW follow-up program, with a focus on the searches for short GRBs possibly associated with BNS mergers. We investigate the possible observational strategies and we outline the prospects for the detection of VHE EM counterparts to transient GW events.

ROBAST 3

Okumura A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The ROOT-based simulator for ray tracing (ROBAST) is an open-source C++ library to simulate various types of cosmic-ray (CR) and gamma-ray telescopes. It is used in multiple purposes in all the different telescope designs of the Cherenkov Telescope Array and is a promising tool for use in other future projects in optics simulations. We have released ROBAST 3 that supports interference calculations in multilayer coating in addition to geometrical optics. Here, we present its new functionality and several recent applications in future CR telescopes.

Reconstruction of stereoscopic CTA events using deep learning with CTLearn

Miener T., Nieto D., Brill A., Spencer S., Contreras J.L., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA), conceived as an array of tens of imaging atmospheric Cherenkov telescopes (IACTs), is an international project for a next-generation ground-based gamma-ray observatory, aiming to improve on the sensitivity of current-generation instruments a factor of five to ten and provide energy coverage from 20 GeV to more than 300 TeV. Arrays of IACTs probe the very-high-energy gamma-ray sky. Their working principle consists of the simultaneous observation of air showers initiated by the interaction of very-high-energy gamma rays and cosmic rays with the atmosphere. Cherenkov photons induced by a given shower are focused onto the camera plane of the telescopes in the array, producing a multi-stereoscopic record of the event. This image contains the longitudinal development of the air shower, together with its spatial, temporal, and calorimetric information. The properties of the originating very-high-energy particle (type, energy, and incoming direction) can be inferred from those images by reconstructing the full event using machine learning techniques. In this contribution, we present a purely deep-learning driven, full-event reconstruction of simulated, stereoscopic IACT events using CTLearn. CTLearn is a package that includes modules for loading and manipulating IACT data and for running deep learning models, using pixel-wise camera data as input.

Reconstruction of extensive air shower images of the first Large Size Telescope prototype of CTA using a novel likelihood technique

Emery G., Alispach C., Dalchenko M., Foffano L., Heller M., Montaruli T., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Escudero J., Fiasson A., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T., Inome Y., Iori M., Ishio K., Iwamura Y., Jacquemont M., Jimenez Martinez I.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Ground-based gamma-ray astronomy aims at reconstructing the energy and direction of gamma rays from the extensive air showers they initiate in the atmosphere. Imaging Atmospheric Cherenkov Telescopes (IACT) collect the Cherenkov light induced by secondary charged particles in extensive air showers (EAS), creating an image of the shower in a camera positioned in the focal plane of optical systems. This image is used to evaluate the type, energy and arrival direction of the primary particle that initiated the shower. This contribution shows the results of a novel reconstruction method based on likelihood maximization. The novelty with respect to previous likelihood reconstruction methods lies in the definition of a likelihood per single camera pixel, accounting not only for the total measured charge, but also for its development over time. This leads to more precise reconstruction of shower images. The method is applied to observations of the Crab Nebula acquired with the Large Size Telescope prototype (LST-1) deployed at the northern site of the Cherenkov Telescope Array.

Prototype Schwarzschild-Couder Telescope for the Cherenkov Telescope Array: Commissioning the Optical System

Ribeiro D., Adams C.B., Ambrosi G., Ambrosio M., Aramo C., Batista P.I., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Buckley J.H., Cameron R.A., Canestrari R., Capasso M., Caprai M., Covault C.E., Depaoli D., Di Venere L., Errando M., Fegan S., Feng Q., Fiandrini E., Furniss A., Gent A., Giglietto N., Giordano F., Giro E., Halliday R., Hervet O., Humensky T.B., Incardona S., Ionica M., Jin W., Kieda D., Licciulli F., Loporchio S., Marsella G., Masone V., Meagher K., Meures T., Mode B.A.W., Mognet S.A.I., Mukherjee R., Nieto D., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Pareschi G., Di Pierro F., Pueschel E., Riitano L., Roache E., Rousselle J., Rugliancich A., Santander M., Shang R., Stiaccini L., Taylor L.P., Tosti L., Tovmassian G., Tripodo G., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V.V., Williams D.A., Yu P.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

A prototype Schwarzschild-Couder Telescope (pSCT) has been constructed at the Fred Lawrence Whipple Observatory as a candidate for the medium-sized telescopes of the Cherenkov Telescope Array Observatory (CTAO). CTAO is currently entering early construction phase of the project and once completed it will vastly improve very high energy gamma-ray detection component in multiwavelength and multi-messenger observations due to significantly improved sensitivity, angular resolution and field of view comparing to the current generation of the ground-based gamma-ray observatories H.E.S.S., MAGIC and VERITAS. The pSCT uses a dual aspheric mirror design with a 9.7 m primary mirror and 5.4 m secondary mirror, both of which are segmented. The Schwarzschild-Couder (SC) optical system (OS) selected for the prototype telescope achieves wide field of view of 8 degrees and simultaneously reduces the focal plane plate scale allowing an unprecedented compact (0.78m diameter) implementation of the high-resolution camera (6mm/0.067deg per imaging pixel with 11, 328 pixels) based on the silicon photo-multipliers (SiPMs). The OS of the telescope is designed to eliminate spherical and comatic aberrations and minimize astigmatism to radically improve off-axis imaging and consequently angular resolution across all the field of view with respect to the conventional single-mirror telescopes. Fast and high imaging resolution OS of the pSCT comes with the challenging submillimeter-precision custom alignment system, which was successfully demonstrated with an on-axis point spread function (PSF) of 2.9 arcmin prior to the first-light detection of the Crab Nebula in 2020. Ongoing commissioning activities aim to meet the on-axis PSF design goal of 2.6 arcmin, verify the off-axis performance of the pSCT OS, and develop techniques to maintain alignment stability over telescope structural deformations from pointing and temperature variations. In this contribution, we report on the commissioning status, the optical alignment procedures adopted for segmented OS, and alignment progress to verify and validate design requirements.

Prototype Open Event Reconstruction Pipeline for the Cherenkov Telescope Array

Nöthe M., Kosack K., Nickel L., Peresano M., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the next-generation gamma-ray observatory currently under construction. It will improve over the current generation of imaging atmospheric Cherenkov telescopes (IACTs) by a factor of five to ten in sensitivity and it will be able to observe the whole sky from a combination of two sites: a northern site in La Palma, Spain, and a southern one in Paranal, Chile. CTA will also be the first open gamma-ray observatory. Accordingly, the data analysis pipeline is developed as open-source software. The event reconstruction pipeline accepts raw data of the telescopes and processes it to produce suitable input for the higher-level science tools. Its primary tasks include reconstructing the physical properties of each recorded shower and providing the corresponding instrument response functions. ctapipe is a framework providing algorithms and tools to facilitate raw data calibration, image extraction, image parameterization and event reconstruction. Its main focus is currently the analysis of simulated data but it has also been successfully applied for the analysis of data obtained with the first CTA prototype telescopes, such as the Large-Sized Telescope 1 (LST-1). pyirf is a library to calculate IACT instrument response functions, needed to obtain physics results like spectra and light curves, from the reconstructed event lists. Building on these two, protopipe is a prototype for the event reconstruction pipeline for CTA. Recent developments in these software packages will be presented.

Prospects for Galactic transient sources detection with the Cherenkov Telescope Array

López-Oramas A., Bulgarelli A., Chaty S., Chernyakova M., Gnatyk R., Hnatyk B., Kantzas D., Markoff S., McKeague S., Mereghetti S., Mestre E., di Piano A., Romano P., Sadeh I., Sergijenko O., Sidoli L., Spolon A., de Ona Wilhelmi E., Piano G., Zampieri L., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Several types of Galactic sources, like magnetars, microquasars, novae or pulsar wind nebulae flares, display transient emission in the X-ray band. Some of these sources have also shown emission at MeV-GeV energies. However, none of these Galactic transients have ever been detected in the very-high-energy (VHE; E>100 GeV) regime by any Imaging Air Cherenkov Telescope (IACT). The Galactic Transient task force is a part of the Transient Working group of the Cherenkov Telescope Array (CTA) Consortium. The task force investigates the prospects of detecting the VHE counterpart of such sources, as well as their study following Target of Opportunity (ToO) observations. In this contribution, we will show some of the results of exploring the capabilities of CTA to detect and observe Galactic transients; we assume different array configurations and observing strategies.

Physics Performance of the Large-Sized Telescope prototype of the Cherenkov Telescope Array

Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T., Inome Y., Iori M., Ishio K., Iwamura Y., Jacquemont M., Jimenez Martinez I., Jouvin L., Jurysek J.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Large-Sized Telescope (LST) prototype of the future Cherenkov Telescope Array (CTA) is located at the Northern site of CTA, on the Canary Island of La Palma. It is designed to provide optimal performance in the lowest part of the energy range covered by CTA, observing gamma rays down to energies of tens of GeV. The LST prototype started performing astronomical observations in November 2019 during the commissioning of the telescope and it has been taking data since then. In this contribution, we will present the tuning of the characteristics of the telescope in the Monte Carlo (MC) simulations to describe the data obtained, the estimation of its angular and energy resolution, and an evaluation of its sensitivity, both with simulations and with observations of the Crab Nebula.

Performance of the Cherenkov Telescope Array in the presence of clouds

Pecimotika M., Adamczyk K., Prester D.D., Gueta O., Hrupec D., Maier G., Mićanović S., Pavletić L., Sitarek J., Sobczyńska D., Szanecki M., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the future ground-based observatory for gamma-ray astronomy at very high energies. The atmosphere is an integral part of every Cherenkov telescope. Different atmospheric conditions, such as clouds, can reduce the fraction of Cherenkov photons produced in air showers that reach ground-based telescopes, which may affect the performance. Decreased sensitivity of the telescopes may lead to misconstructed energies and spectra. This study presents the impact of various atmospheric conditions on CTA performance. The atmospheric transmission in a cloudy atmosphere in the wavelength range from 203 nm to 1000 nm was simulated for different cloud bases and different optical depths using the MODerate resolution atmospheric TRANsmission (MODTRAN) code. MODTRAN output files were used as inputs for generic Monte Carlo simulations. The analysis was performed using the MAGIC Analysis and Reconstruction Software (MARS) adapted for CTA. As expected, the effects of clouds are most evident at low energies, near the energy threshold. Even in the presence of dense clouds, high-energy gamma rays may still trigger the telescopes if the first interaction occurs lower in the atmosphere, below the cloud base. A method to analyze very high-energy data obtained in the presence of clouds is presented. The systematic uncertainties of the method are evaluated. These studies help to gain more precise knowledge about the CTA response to cloudy conditions and give insights on how to proceed with data obtained in such conditions. This may prove crucial for alert-based observations and time-critical studies of transient phenomena.

Performance of a proposed event-type based analysis for the Cherenkov Telescope Array

Hassan T., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E., Bernardos M.I., Bernlöhr K.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next-generation observatory in the field of very-high-energy (20 GeV to 300 TeV) gamma-ray astroparticle physics. Classically, data analysis in the field maximizes sensitivity by applying quality cuts on the data acquired. These cuts, optimized using Monte Carlo simulations, select higher quality events from the initial dataset. Subsequent steps of the analysis typically use the surviving events to calculate one set of instrument response functions (IRFs). An alternative approach is the use of event types, as implemented in experiments such as the Fermi-LAT. In this approach, events are divided into sub-samples based on their reconstruction quality, and a set of IRFs is calculated for each sub-sample. The sub-samples are then combined in a joint analysis, treating them as independent observations. This leads to an improvement in performance parameters such as sensitivity, angular and energy resolution. Data loss is reduced since lower quality events are included in the analysis as well, rather than discarded. In this study, machine learning methods will be used to classify events according to their expected angular reconstruction quality. We will report the impact on CTA high-level performance when applying such an event-type classification, compared to the classical procedure.

Monte Carlo Simulations and Validation of NectarCAM, a Medium Sized Telescope Camera for CTA

Armstrong T.P., Costantini H., Glicenstein J.F., Lenain J.P., Schwanke U., Tavernier T., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The upcoming Cherenkov Telescope Array (CTA) ground-based gamma-ray observatory will open up our view of the very high energy Universe, offering an improvement in sensitivity of 5-10 times that of previous experiments. NectarCAM is one of the proposed cameras for the Medium-Sized Telescopes (MST) which have been designed to cover the core energy range of CTA, from 100 GeV to 10 TeV. The final camera will be capable of GHz sampling and provide a field of view of 8 degrees with its 265 modules of 7 photomultiplier each (for a total of 1855 pixels). In order to validate the performance of NectarCAM, a partially-equipped prototype has been constructed consisting of only the inner 61-modules. It has so far undergone testing at the integration test-bench facility in CEA Paris-Saclay (France) and on a prototype of the MST structure in Adlershof (Germany). To characterize the performance of the prototype, Monte Carlo simulations were conducted using a detailed model of the 61 module camera in the CORSIKA/sim_telarray framework. This contribution provides an overview of this work including the comparison of trigger and readout performance on test-bench data and trigger and image parameterization performance during on-sky measurements.

Monitoring the pointing of the prototype LST-1 using star reconstruction in the Cherenkov camera

Foffano L., Carosi A., Dalchenko M., Heller M., Della Volpe D., Montaruli T., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T., Inome Y., Iori M., Ishio K., Iwamura Y., Jacquemont M., Jimenez Martinez I., Jouvin L.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The first Large-Sized Telescope (LST-1) proposed for the forthcoming Cherenkov Telescope Array (CTA) has started to operate in 2019 in La Palma. The large structure of LST-1 - with a 23 m mirror dish diameter - imposes a strict control of its deformations that could affect the pointing accuracy and its overall performance. According to CTA specifications that are conceived to resolve e.g. the fine structure of galactic sources, the LST post-calibration pointing accuracy should be better than 14 arcseconds. To fulfill this requirement, the telescope pointing precision is monitored with two dedicated CCD cameras located at the dish center. The analysis of their images allows us to disentangle different systematic deformations of the structure. In this work, we investigate a complementary approach that offers the possibility to monitor the pointing of the telescope during the acquisition of sky data. After properly cleaning the events from the Cherenkov showers, the reconstructed positions of the stars imaged in the camera field of view are compared to their nominal expected positions in catalogues. This provides a direct measurement of the telescope pointing, that can be used to cross-check the other methods and as a real-time monitoring of the optical properties of the telescope and of the pointing corrections applied by the bending models. Additionally, this method benefits from not relying on specific hardware or dedicated observations. In this contribution we will illustrate this analysis and show results based on simulations of LST-1.

HAWC J2227+610: a potential PeVatron candidate for the CTA in the northern hemisphere

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Recent observations of the gamma-ray source HAWC J2227+610 by Tibet AS+MD and LHAASO confirm the special interest of this source as a galactic PeVatron candidate in the northern hemisphere. HAWC J2227+610 emits Very High Energy (VHE) gamma-rays up to 500 TeV, from a region coincident with molecular clouds and significantly displaced from the nearby pulsar J2229+6114. Even if this morphology favours an hadronic origin, both leptonic or hadronic models can describe the current VHE gamma-ray emission. The morphology of the source is not well constrained by the present measurements and a better characterisation would greatly help the understanding of the underlying particle acceleration mechanisms. The Cherenkov Telescope Array (CTA) will be the future most sensitive Imaging Atmospheric Cherenkov Telescope and, thanks to its unprecedented angular resolution, could contribute to better constrain the nature of this source. The present work investigates the potentiality of CTA to study the morphology and the spectrum of HAWC J2227+610. For this aim, the source is simulated assuming the hadronic model proposed by the Tibet AS+MD collaboration, recently fitted on multi-wavelength data, and two spatial templates associated to the source nearby molecular clouds. Different CTA layouts and observation times are considered. A 3D map based analysis shows that CTA is able to significantly detect the extension of the source and to attribute higher detection significance to the simulated molecular cloud template compared to the alternative one. CTA data does not allow to disentangle the hadronic and the leptonic emission models. However, it permits to correctly reproduce the simulated parent proton spectrum characterized by a ∼ 500 TeV cutoff.

First follow-up of transient events with the CTA Large Size Telescope prototype

Kobayshi Y., Sanchez D., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T., Inome Y., Iori M., Ishio K., Iwamura Y., Jacquemont M., Jimenez Martinez I.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The recent detection of a very high energy (VHE) emission from Gamma-Ray Bursts (GRBs) above 100 GeV performed by the MAGIC and H.E.S.S. collaborations, has represented a significant, long-awaited result for the VHE astrophysics community. Although these results' scientific impact has not yet been fully exploited, the possibility to detect VHE gamma-ray signals from GRBs has always been considered crucial for clarifying the poorly known physics of these objects. Furthermore, the discovery of high-energy neutrinos and gravitational waves associated with astrophysical sources have definitively opened the era of multi-messenger astrophysics, providing unique insights into the physics of extreme cosmic accelerators. In the near future, the Cherenkov Telescope Array (CTA) will play a major role in these observations. Within this framework, the Large Size Telescopes (LSTs) will be the instruments best suited to significantly impact on short time-scale transients follow-up thanks to their fast slewing and large effective area. The observations of the early emission phase of a wide range of transient events with good sensitivity below 100 GeV will allow us to open new opportunities for time-domain astrophysics in an energy range not affected by selective absorption processes typical of other wavelengths. In this contribution, we will report about the observational program and first transients follow-up observations performed by the LST-1 telescope currently in its commissioning phase on La Palma, Canary Islands, the CTA northern hemisphere site.

Exploring the population of Galactic very-high-energy γ-ray sources

Steppa C., Egberts K., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E., Bernardos M.I.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

At very high energies (VHE), the emission of γ rays is dominated by discrete sources. Due to the limited resolution and sensitivity of current-generation instruments, only a small fraction of the total Galactic population of VHE γ-ray sources has been detected significantly. The larger part of the population can be expected to contribute as a diffuse signal alongside emission originating from propagating cosmic rays. Without quantifying the source population, it is not possible to disentangle these two components. Based on the H.E.S.S. Galactic plane survey, a numerical approach has been taken to develop a model of the population of Galactic VHE γ-ray sources, which is shown to account accurately for the observational bias. We present estimates of the absolute number of sources in the Galactic Plane and their contribution to the total VHE γ-ray emission for five different spatial source distributions. Prospects for CTA and its ability to constrain the model are discussed. Finally, first results of an extension of our modelling approach using machine learning to extract more information from the available data set are presented.

Development of an advanced SiPM camera for the Large Size Telescope of the Cherenkov Telescope Array Observatory

Bellato M., Bergnoli A., Bernasconi E., Biland A., Charbon E., Corti D., Gascón D., Gómez S., Ziȩtara K., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Silicon photomultipliers (SiPMs) have become the baseline choice for cameras of the small-sized telescopes (SSTs) of the Cherenkov Telescope Array (CTA). On the other hand, SiPMs are relatively new to the field and covering large surfaces and operating at high data rates still are challenges to outperform photomultipliers (PMTs). The higher sensitivity in the near infra-red and longer signals compared to PMTs result in higher night sky background rate for SiPMs. However, the robustness of the SiPMs represents a unique opportunity to ensure long-term operation with low maintenance and better duty cycle than PMTs. The proposed camera for large size telescopes will feature 0.05◦ pixels, low power and fast front-end electronics and a fully digital readout. In this work, we present the status of dedicated simulations and data analysis for the performance estimation. The design features and the different strategies identified, so far, to tackle the demanding requirements and the improved performance are described.

Detection of the Crab Nebula by the prototype Schwarzschild-Couder Telescope

Adams C.B., Ambrosi G., Ambrosio M., Aramo C., Batista P.I., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Brown A.M., Buckley J.H., Cameron R.A., Canestrari R., Capasso M., Caprai M., Covault C.E., Depaoli D., Di Venere L., Errando M., Fegan S., Feng Q., Fiandrini E., Furniss A., Gent A., Giglietto N., Giordano F., Giro E., Halliday R., Hervet O., Holder J., Humensky T.B., Incardona S., Ionica M., Jin W., Kieda D., Licciulli F., Loporchio S., Marsella G., Masone V., Meagher K., Meures T., Mode B.A.W., Mognet S.A.I., Mukherjee R., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Pareschi G., Di Pierro F., Pueschel E., Ribeiro D., Riitano L., Roache E., Rousselle J., Rugliancich A., Santander M., Shang R., Stiaccini L., Tajima H., Taylor L.P., Tosti L., Tovmassian G., Tripodo G., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V.V., Williams D.A., Zink A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Schwarzschild-Couder Telescope (SCT) is a medium-sized telescope technology proposed for the Cherenkov Telescope Array. It uses a novel dual-mirror optical design that removes comatic aberrations across its entire field of view. The SCT camera employs high-resolution silicon photomultiplier (SiPM) sensors with a pixel size of 4 arcminutes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. An observing campaign in 2020, with a partial camera of 1600 pixels (2.7 degrees by 2.7 degrees field of view) resulted in detection of the Crab Nebula at 8.6 sigma statistical significance. Work on the pSCT camera and optical system is ongoing to improve performance and prepare for an upcoming camera upgrade. The pSCT camera upgrade will replace the current camera modules with improved SiPMs and readout electronics and will expand the camera to its full design field of view of 8 degrees in diameter (11,328 pixels). The fully upgraded pSCT will enable next-generation very-high-energy gamma-ray astrophysics through excellent background rejection and angular resolution. In this presentation we describe first results from the successful operation of the pSCT and future plans.

Detection methods for the Cherenkov Telescope Array at very-short exposure times

Di Piano A., Bulgarelli A., Fioretti V., Baroncelli L., Parmiggiani N., Longo F., Stamerra A., López-Oramas A., Stratta G., De Cesare G., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Aschersleben J., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next generation ground-based observatory for very-high-energy (VHE) gamma-ray astronomy, with the deployment of tens of highly sensitive and fast-reacting Cherenkov telescopes. It will cover a wide energy range (20 GeV - 300 TeV) with unprecedented sensitivity. To maximize the scientific return, the observatory will be provided with an online software system that will perform the first analysis of scientific data in real-time. This study investigates the precision and accuracy of available science tools and analysis techniques for the short-term detection of gamma-ray sources, in terms of sky localization, detection significance and, if significant detection is achieved, a first estimation of the integral photon flux. The scope is to evaluate the feasibility of the algorithms' implementation in the real-time analysis of CTA. In this contribution we present a general overview of the methods and some of the results for the test case of the short-term detection of a gamma-ray burst afterglow, as the VHE counterpart of a gravitational wave event.

Design and performance of the prototype Schwarzschild-Couder Telescope camera

Taylor L.P., Adams C.B., Ambrosi G., Ambrosio M., Aramo C., Batista P.I., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Brown A.M., Buckley J.H., Cameron R.A., Capasso M., Caprai M., Covault C.E., Depaoli D., Di Venere L., Errando M., Fegan S., Feng Q., Fiandrini E., Furniss A., Gent A., Giglietto N., Giordano F., Halliday R., Hervet O., Humensky T.B., Incardona S., Ionica M., Jin W., Kieda D., Licciulli F., Loporchio S., Marsella G., Masone V., Meagher K., Meures T., Mode B.A.W., Mognet S.A.I., Mukherjee R., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Pareschi G., Di Pierro F., Pueschel E., Ribeiro D., Riitano L., Roache E., Ross D., Rousselle J., Rugliancich A., Santander M., Shang R., Stiaccini L., Tajima H., Taylor L.P., Tosti L., Tovmassian G., Tripodo G., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V.V., Watson J.J., White R., Williams D.A., Zink A.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma-ray astronomy. An innovative 9.7 m aperture, dual-mirror Schwarzschild-Couder Telescope (SCT) design is a candidate design for CTA Medium-Sized Telescopes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. Its camera is currently partially instrumented with 1600 pixels covering a field of view of 2.7 degrees square. The small plate scale of the optical system allows densely packed silicon photomultipliers to be used, which combined with high-density trigger and waveform readout electronics enable the high-resolution camera. The camera's electronics are capable of imaging air shower development at a rate of one billion samples per second. We describe the commissioning and performance of the pSCT camera, including trigger and waveform readout performance, calibration, and absolute GPS time stamping. We also present the upgrade to the camera, which is currently underway. The upgrade will fully populate the focal plane, increasing the field of view to 8 degree diameter, and lower the front-end electronics noise, enabling a lower trigger threshold and improved reconstruction and background rejection.

Deep-learning-driven event reconstruction applied to simulated data from a single Large-Sized Telescope of CTA

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

When very-high-energy gamma rays interact high in the Earth's atmosphere, they produce cascades of particles that induce flashes of Cherenkov light. Imaging Atmospheric Cherenkov Telescopes (IACTs) detect these flashes and convert them into shower images that can be analyzed to extract the properties of the primary gamma ray. The dominant background for IACTs is comprised of air shower images produced by cosmic hadrons, with typical noise-to-signal ratios of several orders of magnitude. The standard technique adopted to differentiate between images initiated by gamma rays and those initiated by hadrons is based on classical machine learning algorithms, such as Random Forests, that operate on a set of handcrafted parameters extracted from the images. Likewise, the inference of the energy and the arrival direction of the primary gamma ray is performed using those parameters. State-of-the-art deep learning techniques based on convolutional neural networks (CNNs) have the potential to enhance the event reconstruction performance, since they are able to autonomously extract features from raw images, exploiting the pixel-wise information washed out during the parametrization process. Here we present the results obtained by applying deep learning techniques to the reconstruction of Monte Carlo simulated events from a single, next-generation IACT, the Large-Sized Telescope (LST) of the Cherenkov Telescope Array (CTA). We use CNNs to separate the gamma-ray-induced events from hadronic events and to reconstruct the properties of the former, comparing their performance to the standard reconstruction technique. Three independent implementations of CNN-based event reconstruction models have been utilized in this work, producing consistent results.

Cross-calibration and combined analysis of the CTA-LST prototype and the MAGIC telescopes

Ohtani Y., Berti A., Depaoli D., Di Pierro F., Green D., Heckmann L., Hütten M., Inada T., López-Coto R., Medina E., Moralejo A., Morcuende D., Pirola G., Strzys M., Suda Y., Vovk I., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory, which will consist of three kinds of telescopes of different sizes. Among those, the Large Size Telescope (LST) will be the most sensitive in the low energy range starting from 20 GeV. The prototype LST (LST-1) proposed for CTA was inaugurated in October 2018 in the northern hemisphere site, La Palma (Spain), and is currently in its commissioning phase. MAGIC is a system of two gamma-ray Cherenkov telescopes of the current generation, located approximately 100 m away from LST-1, that have been operating in stereoscopic mode since 2009. Since LST-1 and MAGIC can observe the same air shower events, we can compare the brightness of showers, estimated energies of gamma rays, and other parameters event by event, which can be used to cross-calibrate the telescopes. Ultimately, by performing combined analyses of the events triggering the three telescopes, we can reconstruct the shower geometry more accurately, leading to better energy and angular resolutions, and a better discrimination of the background showers initiated by cosmic rays. For that purpose, as part of the commissioning of LST-1, we performed joint observations of established gamma-ray sources with LST-1 and MAGIC. Also, we have developed Monte Carlo simulations for such joint observations and an analysis pipeline which finds event coincidence in the offline analysis based on their timestamps. In this work, we present the first detection of an astronomical source, the Crab Nebula, with combined observation of LST-1 and MAGIC. Moreover, we show results of the inter-telescope cross-calibration obtained using Crab Nebula data taken during joint observations with LST-1 and MAGIC.

Commissioning of the camera of the first Large Size Telescope of the Cherenkov Telescope Array

Saito T., Delgado C., Blanch O., Artero M., Barrio J.A., Cassol F., Diaz C., Hadasch D., Hoffmann D., Houles J., Inome Y., Iori M., Jouvin L., Kerszberg D., Kobayashi Y., Kubo H., Martinez G., Mazin D., Moretti E., Nakamori T., Nozaki S., Oka T., Okumura A., Palatiello M., Polo M., Prast J., Sakurai S., Sunada Y., Takahashi M., Takeishi R., Tejedor L.A., Yamamoto T., Yoshida T., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The first Large Size Telescope (LST-1) of the Cherenkov Telescope Array has been operational since October 2018 at La Palma, Spain. We report on the results obtained during the camera commissioning. The noise level of the readout is determined as a 0.2 p.e. level. The gain of PMTs are well equalized within 2% variation, using the calibration flash system. The effect of the night sky background on the signal readout noise as well as the PMT gain estimation are also well evaluated. Trigger thresholds are optimized for the lowest possible gamma-ray energy threshold and the trigger distribution synchronization has been achieved within 1 ns precision. Automatic rate control realizes the stable observation with 1.5% rate variation over 3 hours. The performance of the novel DAQ system demonstrates a less than 10% dead time for 15 kHz trigger rate even with sophisticated online data correction.

Camera Calibration of the CTA-LST prototype

Kobayashi Y., Okumura A., Cassol F., Katagiri H., Sitarek J., Gliwny P., Nozaki S., Nogami Y., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra Gonzalez J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., de Bony de Lavergne M., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Daaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsaasser D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia Lapez R., Giglietto N., Giordano F., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., HÃŒtten M., Inada T., Inome Y., Iori M.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the next-generation gamma-ray observatory that is expected to reach one order of magnitude better sensitivity than that of current telescope arrays. The Large-Sized Telescopes (LSTs) have an essential role in extending the energy range down to 20 GeV. The prototype LST (LST-1) proposed for CTA was built in La Palma, the northern site of CTA, in 2018. LST-1 is currently in its commissioning phase and moving towards scientific observations. The LST-1 camera consists of 1855 photomultiplier tubes (PMTs) which are sensitive to Cherenkov light. PMT signals are recorded as waveforms sampled at 1 GHz rate with Domino Ring Sampler version 4 (DRS4) chips. Fast sampling is essential to achieve a low energy threshold by minimizing the integration of background light from the night sky. Absolute charge calibration can be performed by the so-called F-factor method, which allows calibration constants to be monitored even during observations. A calibration pipeline of the camera readout has been developed as part of the LST analysis chain. The pipeline performs DRS4 pedestal and timing corrections, as well as the extraction and calibration of charge and time of pulses for subsequent higher-level analysis. The performance of each calibration step is examined, and especially charge and time resolution of the camera readout are evaluated and compared to CTA requirements. We report on the current status of the calibration pipeline, including the performance of each step through to signal reconstruction, and the consistency with Monte Carlo simulations.

Application of pattern spectra and convolutional neural networks to the analysis of simulated Cherenkov Telescope Array data

Aschersleben J., Peletier R.F., Vecchi M., Wilkinson M.H.F., Abdalla H., Abe H., Abe S., Abusleme A., Acero F., Acharyya A., Acín Portella V., Ackley K., Adam R., Adams C., Adhikari S.S., Aguado-Ruesga I., Agudo I., Aguilera R., Aguirre-Santaella A., Aharonian F., Alberdi A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Alves Batista R., Amans J.P., Amati L., Amato E., Ambrogi L., Ambrosi G., Ambrosio M., Ammendola R., Anderson J., Anduze M., Angüner E.O., Antonelli L.A., Antonuccio V., Antoranz P., Anutarawiramkul R., Aragunde Gutierrez J., Aramo C., Araudo A., Araya M., Arbet-Engels A., Arcaro C., Arendt V., Armand C., Armstrong T., Arqueros F., Arrabito L., Arsioli B., Artero M., Asano K., Ascasíbar Y., Ashley M., Attinà P., Aubert P., Singh C.B., Baack D., Babic A., Backes M., Baena V., Bajtlik S., Baktash A., Balazs C., Balbo M., Ballester O., Ballet J., Balmaverde B., Bamba A., Bandiera R., Baquero Larriva A., Barai P., Barbier C., Barbosa Martins V., Barcelo M., Barkov M., Barnard M., Baroncelli L., Barres de Almeida U., Barrio J.A., Bastieri D., Batista P.I., Batkovic I., Bauer C., Bautista-González R., Baxter J., Becciani U., Becerra González J., Becherini Y., Beck G., Becker Tjus J., Bednarek W., Belfiore A., Bellizzi L., Belmont R., Benbow W., Berge D., Bernardini E.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) will be the next generation gamma-ray observatory and will be the major global instrument for very-high-energy astronomy over the next decade, offering 5 − 10 × better flux sensitivity than current generation gamma-ray telescopes. Each telescope will provide a snapshot of gamma-ray induced particle showers by capturing the induced Cherenkov emission at ground level. The simulation of such events provides images that can be used as training data for convolutional neural networks (CNNs) to determine the energy of the initial gamma rays. Compared to other state-of-the-art algorithms, analyses based on CNNs promise to further enhance the performance to be achieved by CTA. Pattern spectra are commonly used tools for image classification and provide the distributions of the shapes and sizes of various objects comprising an image. The use of relatively shallow CNNs on pattern spectra would automatically select relevant combinations of features within an image, taking advantage of the 2D nature of pattern spectra. In this work, we generate pattern spectra from simulated gamma-ray events instead of using the raw images themselves in order to train our CNN for energy reconstruction. This is different from other relevant learning and feature selection methods that have been tried in the past. Thereby, we aim to obtain a significantly faster and less computationally intensive algorithm, with minimal loss of performance.

Analysis of the Cherenkov Telescope Array first Large-Sized Telescope real data using convolutional neural networks

Vuillaume T., Jacquemont M., de Bony de Lavergne M., Sanchez D.A., Poireau V., Maurin G., Benoit A., Lambert P., Lamanna G., Abe H., Aguasca A., Agudo I., Antonelli L.A., Aramo C., Armstrong T., Artero M., Asano K., Ashkar H., Aubert P., Baktash A., Bamba A., Baquero Larriva A., Baroncelli L., Barres de Almeida U., Barrio J.A., Batkovic I., Becerra González J., Bernardos M.I., Berti A., Biederbeck N., Bigongiari C., Blanch O., Bonnoli G., Bordas P., Bose D., Bulgarelli A., Burelli I., Buscemi M., Cardillo M., Caroff S., Carosi A., Cassol F., Cerruti M., Chai Y., Cheng K., Chikawa M., Chytka L., Contreras J.L., Cortina J., Costantini H., Dalchenko M., De Angelis A., Deleglise G., Delgado C., Delgado Mengual J., della Volpe D., Depaoli D., Di Pierro F., Di Venere L., Díaz C., Dominik R.M., Dominis Prester D., Donini A., Dorner D., Doro M., Elsässer D., Emery G., Escudero J., Fiasson A., Foffano L., Fonseca M.V., Freixas Coromina L., Fukami S., Fukazawa Y., Garcia E., Garcia López R., Giglietto N., Giordano F., Gliwny P., Godinovic N., Green D., Grespan P., Gunji S., Hackfeld J., Hadasch D., Hahn A., Hassan T., Hayashi K., Heckmann L., Heller M., Herrera Llorente J., Hirotani K., Hoffmann D., Horns D., Houles J., Hrabovsky M., Hrupec D., Hui D., Hütten M., Inada T.

Proceedings of Science Vol. 395 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) is the future ground-based gamma-ray observatory and will be composed of two arrays of imaging atmospheric Cherenkov telescopes (IACTs) located in the Northern and Southern hemispheres respectively. The first CTA prototype telescope built on-site, the Large-Sized Telescope (LST-1), is under commissioning in La Palma and has already taken data on numerous known sources. IACTs detect the faint flash of Cherenkov light indirectly produced after a very energetic gamma-ray photon has interacted with the atmosphere and generated an atmospheric shower. Reconstruction of the characteristics of the primary photons is usually done using a parameterization up to the third order of the light distribution of the images. In order to go beyond this classical method, new approaches are being developed using state-of-the-art methods based on convolutional neural networks (CNN) to reconstruct the properties of each event (incoming direction, energy and particle type) directly from the telescope images. While promising, these methods are notoriously difficult to apply to real data due to differences (such as different levels of night sky background) between Monte Carlo (MC) data used to train the network and real data. The GammaLearn project, based on these CNN approaches, has already shown an increase in sensitivity on MC simulations for LST-1 as well as a lower energy threshold. This work applies the GammaLearn network to real data acquired by LST-1 and compares the results to the classical approach that uses random forests trained on extracted image parameters. The improvements on the background rejection, event direction, and energy reconstruction are discussed in this contribution.

Design and performance of the prototype Schwarzschild-Couder telescope camera

Adams Colin B., Ambrosi Giovanni, Ambrosio Michelangelo, Aramo Carla, Arlen Timothy, Benbow Wystan, Bertucci Bruna, Bissaldi Elisabetta, Biteau Jonathan, Bitossi Massimiliano, Boiano Alfonso, Bonavolonta Carmela, Bose Richard, Bouvier Aurelien, Buscemi Mario, Brill Aryeh, Brown Anthony M., Buckley James H., Canestrari Rodolfo, Capasso Massimo, Caprai Mirco, Coppi Paolo, Covault Corbin E., Depaoli Davide, Di Venere Leonardo, Errando Manel, Fegan Stephan, Feng Qi, Fiandrini Emanuele, Furniss Amy, Garczarczyk Markus, Gent Alasdair, Giglietto Nicola, Giordano Francesco, Giro Enrico, Halliday Robert, Hervet Olivier, Hughes Gareth, Incardona Simone, Humensky Thomas B., Ionica Maria, Jin Weidong, Johnson Caitlin A., Kieda David, Krennrich Frank, Kuznetsov Andrey, Lapington Jon, Licciulli Francesco, Loporchio Serena, Marsella Giovanni, Masone Vincenzo, Meagher Kevin, Meures Thomas, Mode Brent A. W., Mognet Samuel A. I, Mukherjee Reshmi, Okumura Akira, Pantaleo Francesca R., Paoletti Riccardo, Di Pierro Federico, Ribeiro Deivid, Riitano Luca, Roache Emmet, Ross Duncan, Rousselle Julien, Rugliancich Andrea, Santander Marcos, Schneider Michael, Schoorlemmer Harm, Shang Ruo-Yu, Stevenson Brandon, Stiaccini Leonardo, Tajima Hiroyasu, Taylor Leslie P., Thornhill Julian, Tosti Luca, Tripodo Giovanni, Vagelli Valerio, Valentino Massimo, Vandenbroucke Justin, Vassiliev Vladimir V., Wakely Scott P., Watson Jason J., White Richard, Wilcox Patrick, Williams David A., Wood Matthew, Yu Peter, Zink Adrian

JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS Vol. 8 ( 1 ) 2022.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Astronomical Telescopes, Instruments, and Systems

The prototype Schwarzschild-Couder Telescope (pSCT) is a candidate for a medium-sized telescope in the Cherenkov Telescope Array. The pSCT is based on a dual-mirror optics design that reduces the plate scale and allows for the use of silicon photomultipliers as photodetectors. The prototype pSCT camera currently has only the central sector instrumented with 25 camera modules (1600 pixels), providing a 2.68-deg field of view (FoV). The camera electronics are based on custom TARGET (TeV array readout with GSa/s sampling and event trigger) application-specific integrated circuits. Field programmable gate arrays sample incoming signals at a gigasample per second. A single backplane provides camera-wide triggers. An upgrade of the pSCT camera that will fully populate the focal plane is in progress. This will increase the number of pixels to 11,328, the number of backplanes to 9, and the FoV to 8.04 deg. Here, we give a detailed description of the pSCT camera, including the basic concept, mechanical design, detectors, electronics, current status, and first light.

DOI： 10.1117/1.JATIS.8.1.014007

The Small-Sized Telescope of CTAO

Tagliaferri G., Antonelli A., Arnesen T., Aschersleben J., Attina P., Balbo M., Bang S., Barcelo M., Baryshev A., Bellassai G., Berge D., Bicknell C., Bigongiari C., Bonnoli G., Bouley F., Brown A., Bulgarelli A., Cappi M., Caraveo P., Caschera S., Chadwick P., Conte F., Cotter G., Cristofari P., De Frondat F., Dal Pino E. De Gouveia, De Simone N., Depaoli D., Dournaux J-L, Duffy C., Einecke S., Fermino C., Funk S., Gargano C., Giavitto G., Giuliani A., Greenshaw T., Hinton J., Huet J-M, Iovenitti S., La Palombara N., Lapington J., Laporte P., Leach S., Lessio L., Leto G., Lloyd S., Lucarelli F., Lombardi S., Macchi A., Martinetti E., Micciche A., Millul R., Mineo T., Mitsunari T., Nayak A., Nicotra G., Okumura A., Pareschi G., Penno M., Prokoph H., Rebert E., Righi C., Rulten C., Russo F., Sanchez R. Zanmar, Saturni F. G., Schaefer J., Schwab B., Scuderi S., Sironi G., Sliusar V, Sol H., Spencer S., Stamerra A., Tajima H., Tavecchio F., Tosti G., Trois A., Vecchi M., Vercellone S., Vink J., Walter R., Watson J., White R., Zanin R., Zampieri L., Zech A., Zink A.

GROUND-BASED AND AIRBORNE TELESCOPES IX Vol. 12182 2022

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of SPIE - The International Society for Optical Engineering

The Cherenkov Telescope Array Observatory (CTAO) consists of three types of telescopes: large-sized (LST), mediumsized (MST), and small-sized (SST), distributed in two observing sites (North and South). For the CTA South "Alpha Configuration"the construction and installation of 37 (+5) SST telescopes (a number that could increase up to 70 in future upgrades) are planned. The SSTs are developed by an international consortium of institutes that will provide them as an in-kind contribution to CTAO. The SSTs rely on a Schwarzschild-Couder-like dual-mirror polynomial optical design, with a primary mirror of 4 m diameter, and are equipped with a focal plane camera based on SiPM detectors covering a field of view of ∼9°. The current SST concept was validated by developing the prototype dual-mirror ASTRI-Horn Cherenkov telescope and the CHEC-S SiPM focal plane camera. In this contribution, we will present an overview of the SST key technologies, the current status of the SST project, and the planned schedule.

DOI： 10.1117/12.2627956

Camera design and performance of the prototype Schwarzschild-Couder Telescope for the Cherenkov Telescope Array

Adams C., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontá C., Bose R., Brill A., Buckley J.H., Caprai M., Di Venere L., Feng Q., Fiandrini E., Giglietto N., Giordano F., Hervet O., Hughes G., Humensky T.B., Ionica M., Jin W., Kaaret P., Kieda D., Kim B., Licciulli F., Loporchio S., Masone V., Meures T., Mode B.A.W., Mukherjee R., Pantaleo F.R., Okumura A., Petrashyk A., Powell J., Paoletti R., Ribeiro D., Rugliancich A., Santander M., Shang R., Stevenson B., Stiaccini L., Taylor L.P., Tosti L., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V., Wilcox P., Williams D.A.

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Schwarzschild-Couder Telescope (SCT) is a candidate technology for a medium-sized telescope within the Cherenkov Telescope Array, the next generation ground based observatory for very high energy gamma ray astronomy. The SCT uses a novel two-mirror design and is expected to yield improvements in field of view and image resolution compared to traditional Cherenkov telescopes based on single-mirror-dish optics. To match the improved optical resolution, challenging requirements of high channel count and density at low power consumption must be overcome by the camera. The prototype camera, currently commissioned and tested on the prototype SCT, has been developed based on millimeter scale SiPM pixels and a custom high density digitizer ASIC, TARGET, to provide 1600 pixels spanning a 2.7 degree field of view while being able to sample nanosecond photon pulses. It is mechanically designed to allow for an upgrade to 11,328 pixels covering a field of view of 8 degrees and demonstrating the full potential of the technology. The camera was installed on the telescope in 2018. We will present its design and performance including first light data.

Using Muon Rings for the Optical Throughput Calibration of the Cherenkov Telescope Array

Gaug M., Fegan S., Mitchell A., Maccarone M.C., Mineo T., Okumura A.

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

Muon ring images observed with Imaging Atmospheric Cherenkov Telescopes (IACTs) provide a powerful means to calibrate the optical throughput of IACTs and monitor their optical point spread function. We investigate whether muons ring images can be used as the primary optical throughput calibration method for the telescopes of the future Cherenkov Telescope Array (CTA) and find several additional systematic effects in comparison to previous works. To ensure that the method achieves the accuracy required by CTA, these systematic effects need to be taken into account and minor modifications to the hardware and analysis are necessary. We derive analytic estimates for the expected muon data rates to be used for optical throughput calibration, monitoring of the optical point spread function, with achievable statistical and systematic uncertainties, and explore the potential of muon ring images as a secondary method of camera pixel flat-fielding.

Upgrading the Prototype Schwarzschild-Couder Telescope Camera to a Wide-Field, High-Resolution Instrument

Adams C., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Buckley J.H., Caprai M., Covault C.E., Di Venere L., Feng Q., Fiandrini E., Gent A., Giglietto N., Giordano F., Halliday R., Hervet O., Hughes G., Humensky T.B., Ionica M., Jin W., Kaaret P., Kieda D., Kim B., Licciulli F., Loporchio S., Masone V., Meures T., Mode B.A.W., Mukherjee R., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Petrashyk A., Powell J., Powell K., Ribeiro D., Rugliancich A., Santander M., Shang R., Stevenson B., Stiaccini L., Taylor L.P., Tosti L., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V., Wilcox P., Williams D.A.

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Schwarzschild-Couder Telescope (SCT) is a candidate technology for a medium-sized telescope within the Cherenkov Telescope Array. It is expected to yield substantial improvements in field of view and image resolution compared to traditional telescopes based on Davies-Cotton optics. To match the improved optical resolution, challenging requirements of high channel count and density at low power consumption have to be met by the camera. An initial prototype camera, with 1600 pixels spanning a 2.7◦ field of view, was installed on the prototype SCT in 2018. A project is now underway to upgrade the camera by increasing its pixel count and field of view by factors of 7 and 3, respectively (to 11,328 pixels and 8.0◦). At the same time, the electronics design is being improved in order to lower the gamma-ray energy threshold and thereby provide an instrument especially well-suited for scientific studies related to extended sources and multimessenger astronomy.

The calibration of the first Large-Sized Telescope of the Cherenkov Telescope Array

Sakurai S., Depaoli D., López-Coto R., Becerra González J., Berti A., Blanch O., Cassol F., Chiavassa A., Corti D., De Angelis A., Delgado C., Díaz C., Di Pierro F., Di Venere L., Doro M., Fernández-Barral A., Giordano F., Griffiths S., Hadasch D., Inome Y., Jouvin L., Kerszberg D., Kubo H., López-Oramas A., Mallamaci M., Mariotti M., Martínez G., Masuda S., Mazin D., Moralejo A., Moretti E., Nagayoshi T., Ninci D., Nogués L., Nozaki S., Okumura A., Paoletti R., Penil P., Pillera R., Pio C., Rando R., Rotondo F., Rugliancich A., Saito T., Sunada Y., Suzuki M., Takahashi M., Tejedor L.A., Vallania P., Vigorito C., Yamamoto T., Yoshida T.

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA) represents the next generation of very high-energy gamma-ray observatory, which will provide broad coverage of gamma rays from 20 GeV to 300 TeV with unprecedented sensitivity. CTA will employ three different sizes of telescopes, and the Large-Sized Telescopes (LSTs) of 23-m diameter dish will provide the sensitivity in the lowest energies down to 20 GeV. The first LST prototype has been inaugurated in October 2018 at La Palma (Canary Islands, Spain) and has entered the commissioning phase. The camera of the LST consists of 265 PMT modules. Each module is equipped with seven high-quantum-efficiency Photomultiplier Tubes (PMTs), a slow control board, and a readout board. Ensuring high uniformity and precise characterization of the camera is the key aspects leading to the best performance and low systematic uncertainty of the LST cameras. Therefore, prior to the installation on site, we performed a quality check of all PMT modules. Moreover, the absolute calibration of light throughput is essential to reconstruct the amount of light received by the telescope. The amount of light is affected by the atmosphere, by the telescope optical system and camera, and can be calibrated using the ring-shaped images produced by cosmic-ray muons. In this contribution, we will show the results of off-site quality control of PMT modules and on-site calibration using muon rings. We will also highlight the status of the development of Silicon Photomultiplier modules that could be considered as a replacement of PMT modules for further improvement of the camera.

Prototype Schwarzschild-Couder Telescope for the Cherenkov Telescope Array: Commissioning Status of the Optical System

Adams C., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Buckley J.H., Caprai M., Covault C.E., Di Venere L., Fegan S., Feng Q., Fiandrini E., Gent A., Giglietto N., Giordano F., Halliday R., Hervet O., Hughes G., Humensky T.B., Ionica M., Jin W., Kaaret P., Kieda D., Kim B., Licciulli F., Loporchio S., Masone V., Meures T., Mode B.A.W., Mukherjee R., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Petrashyk A., Powell J., Powell K., Ribeiro D., Rousselle J., Rugliancich A., Santander M., Shang R., Stevenson B., Stiaccini L., Taylor L.P., Tosti L., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V., Wilcox P., Williams D.A.

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Cherenkov Telescope Array (CTA), with more than 100 telescopes, will be the largest ever ground-based gamma-ray observatory and is expected to greatly improve on both gamma-ray detection sensitivity and energy coverage compared to current-generation detectors. The 9.7-m Schwarzschild-Couder telescope (SCT) is one of the two candidates for the medium size telescope (MST) design for CTA. The novel aplanatic dual-mirror SCT design offers a wide field-of-view with a compact plate scale, allowing for a large number of camera pixels that improves the angular resolution and reduce the night sky background noise per pixel compared to the traditional single-mirror Davies-Cotton (DC) design of ground-based gamma-ray telescopes. The production, installation, and the alignment of the segmented aspherical mirrors are the main challenges for the realization of the SCT optical system. In this contribution, we report on the commissioning status, the alignment procedures, and initial alignment results during the initial commissioning phase of the optical system of the prototype SCT.

Development and operations of INFN optical modules for the SCT Telescope camera proposed for the Cherenkov Telescope Array Observatory

Proceedings of Science Vol. 358 2021.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of Science

The Schwarzschild-Couder Telescope (SCT) is a proposal for the Medium Size Telescopes of the Cherenkov Telescope Array. Its concept is based on a two-mirror optical system designed to improve the telescope field of view and image resolution with respect to the single mirror Davies-Cotton solution. The SCT camera is planned to be instrumented with 177 photodetection modules, each composed of 64 Silicon Photomultiplier (SiPM) pixels. The third generation of 6×6 mm2 high density NUV SiPMs (NUV-HD3) produced by Fondazione Bruno Kessler (FBK) in collaboration with INFN has been used to equip optical units to be integrated on the upgrade of the camera of the SCT prototype (pSCT). Each optical unit is composed of an array of 16 NUV-HD3 SiPMs coupled with the front-end electronics, which is designed for full-waveform nanosecond readout and digitization using the TARGET-7 ASIC. Several optical units have been assembled and tested in the laboratories of INFN and have been integrated on the camera of the pSCT telescope, that is currently operating at the Fred Lawrence Whipple Observatory. In this contribution we report on the development, assembly and calibration of the optical units that are currently taking data on the pSCT camera.

Detection of the Crab Nebula with the 9.7 m prototype Schwarzschild-Couder telescope

Adams C. B., Alfaro R., Ambrosi G., Ambrosio M., Aramo C., Arlen T., Batista P. I, Benbow W., Bertucci B., Bissaldi E., Biteau J., Bitossi M., Boiano A., Bonavolonta C., Bose R., Bouvier A., Brill A., Brown A. M., Buckley J. H., Byrum K., Cameron R. A., Canestrari R., Capasso M., Caprai M., Covault C. E., Depaoli D., Errando M., Fegan S., Feng Q., Fiandrini E., Foote G., Fortin P., Funk S., Furniss A., Garfias F., Gent A., Giglietto N., Giordano F., Giro E., Gonzalez M. M., Guarino V, Halliday R., Hervet O., Holder J., Hughes G., Humensky T. B., Ionica M., Iriarte A., Jin W., Johnson C. A., Kaaret P., Kieda D., Kim B., Kuznetsov A., Lapington J. S., Licciulli F., Loporchio S., Masone V, Meagher K., Meures T., Mode B. A. W., Mognet S. A. I, Mukherjee R., Nguyen T., Nieto D., Okumura A., Otte N., La Palombara N., Pantaleo F. R., Paoletti R., Pareschi G., Petrashyk A., Di Pierro F., Pueschel E., Reynolds P. T., Ribeiro D., Richards G., Roache E., Ross D., Rousselle J., Rugliancich A., Ruiz-Diaz-Soto J., Santander M., Schlenstedt S., Schneider M., Scuderi S., Shang R., Sironi G., Stevenson B., Stiaccini L., Tajima H., Taylor L. P., Thornhill J., Tosti L., Tovmassian G., Vagelli V., Valentinoa M., Vandenbroucke J., Vassiliev V. V., Di Venere L., Wakely S. P., Watson J. J., White R., Wilcoxa P., Williams D. A., Wood M., Yu P., Zink A.

ASTROPARTICLE PHYSICS Vol. 128 2021.3

Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre

Acharyya A., Adam R., Adams C., Agudo I, Aguirre-Santaella A., Alfaro R., Alfaro J., Alispach C., Aloisio R., Batista R. Alves, Amati L., Ambrosi G., Anguner E. O., Antonelli L. A., Aramo C., Araudo A., Armstrong T., Arqueros F., Asano K., Ascasibar Y., Ashley M., Balazs C., Ballester O., Baquero Larriva A., Martins V. Barbosa, Barkov M., de Almeida U. Barres, Barrio J. A., Bastieri D., Becerra J., Beck G., Tjus J. Becker, Benbow W., Benito M., Berge D., Bernardini E., Bernloehr K., Berti A., Bertucci B., Beshley V, Biasuzzi B., Biland A., Bissaldi E., Biteau J., Blanch O., Blazek J., Bocchino F., Boisson C., Arbeletche L. Bonneau, Bordas P., Bosnjak Z., Bottacini E., Bozhilov V, Bregeon J., Brill A., Bringmann T., Brown A. M., Brun P., Brun F., Bruno P., Bulgarelli A., Burton M., Burtovoi A., Buscemi M., Cameron R., Capasso M., Caproni A., Capuzzo-Dolcetta R., Caraveo P., Carosi R., Carosi A., Casanova S., Cascone E., Cassol F., Catalani F., Cauz D., Cerruti M., Chadwick P., Chaty S., Chen A., Chernyakova M., Chiaro G., Chiavassa A., Chikawa M., Chudoba J., Colak M., Conforti V, Coniglione R., Conte F., Contreras J. L., Coronado-Blazquez J., Costa A., Costantini H., Cotter G., Cristofari P., D'Ai A., D'Ammando A., Damone L. A., Daniel M. K., Dazzi F., De Angelis A., De Caprio V, dos Anjos R. de Cassia, de Gouveia Dal Pino E. M., De Lotto B., De Martino D., Wilhelmi E. de Ona, De Palma F., de Souza V, Delgado C., Delgado Giler A. G., della Volpe D., Depaoli D., Di Girolamo T., Di Pierro F., Di Venere L., Diebold S., Dmytriiev A., Dominguez A., Donini A., Doro M., Ebr J., Eckner C., Edwards T. D. P., Ekoume T. R. N., Elsaesser D., Evoli C., Falceta-Goncalves D., Fedorova E., Fegan S., Feng Q., Ferrand G., Ferrara G., Fiandrini E., Fiasson A., Filipovic M., Fioretti V, Fiori M., Foffano L., Fontaine G., Fornieri O., Franco F. J., Fukami S., Fukui Y., Gaggero D., Galaz G., Gammaldi V, Garcia E., Garczarczyk M., Gascon D., Gent A., Ghalumyan A., Gianotti F., Giarrusso M., Giavitto G., Giglietto N., Giordano F., Giuliani A., Glicenstein J., Gnatyk R., Goldoni P., Gonzalez M. M., Gourgouliatos K., Granot J., Grasso D., Green J., Grillo A., Gueta O., Gunji S., Halim A., Hassan T., Heller M., Hernandez Cadena S., Hiroshima N., Hnatyk B., Hofmann W., Holder J., Horan D., Horandel J., Horvath P., Hovatta T., Hrabovsky M., Hrupec D., Hughes G., Humensky T. B., Huetten M., Iarlori M., Inada T., Inoue S., Iocco F., Iori M., Jamrozy M., Janecek P., Jin W., Jouvin L., Jurysek J., Karukes E., Katarzynski K., Kazanas D., Kerszberg D., Kherlakian M. C., Kissmann R., Knodlseder J., Kobayashi Y., Kohri K., Komin N., Kubo H., Kushida J., Lamanna G., Lapington J., Laporte P., Leigui de Oliveira M. A., Lenain J., Leone F., Leto G., Lindfors E., Lohse T., Lombardi S., Longo F., Lopez A., Lopez M., Lopez-Coto R., Loporchio S., Luque-Escamilla P. L., Mach E., Maggio C., Maier G., Mallamaci M., Nunes de Almeida R. Malta, Mandat D., Manganaro M., Mangano S., Manico G., Marculewicz M., Mariotti M., Markoff S., Marquez P., Marti J., Martinez O., Martinez M., Martinez G., Martinez-Huerta H., Maurin G., Mazin D., Mbarubucyeye J. D., Miranda D. Medina, Meyer M., Miceli M., Miener T., Minev M., Miranda J. M., Mirzoyan R., Mizuno T., Mode B., Moderski R., Mohrmann L., Molina E., Montaruli T., Moralejo A., Morcuende-Parrilla D., Morselli A., Mukherjee R., Mundell C., Nagai A., Nakamori T., Nemmen R., Niemiec J., Nieto D., Nikolajuk M., Ninci D., Noda K., Nosek D., Nozaki S., Ohira Y., Ohishi M., Ohtani Y., Oka T., Okumura A., Ong R. A., Orienti M., Orito R., Orlandini M., Orlando S., Orlando E., Ostrowski M., Oya I, Pagano I, Pagliaro A., Palatiello M., Pantaleo F. R., Paredes J. M., Pareschi G., Parmiggiani N., Patricelli B., Pavletic L., Pe'er A., Pecimotika M., Perez-Romero J., Persic M., Petruk O., Pfrang K., Piano G., Piatteli P., Pietropaolo E., Pillera R., Pilszyk B., Pintore F., Pohl M., Poireau V, Prado R. R., Prandini E., Prast J., Principe G., Prokoph H., Prouza M., Przybilski H., Puhlhofer G., Pumo M. L., Queiroz F., Quirrenbach A., Raino S., Rando R., Razzaque S., Recchia S., Reimer O., Reisenegger A., Renier Y., Rhode W., Ribeiro D., Ribo M., Richtler T., Rico J., Rieger F., Rinchiuso L., Rizi V, Rodriguez J., Fernandez G. Rodriguez, Rodriguez Ramirez J. C., Rojas G., Romano P., Romeo G., Rosado J., Rowell G., Rudak B., Russo F., Sadeh I, Hatlen E. Saether, Safi-Harb S., Greus F. Salesa, Salina G., Sanchez D., Sanchez-Conde M., Sangiorgi P., Sano H., Santander M., Santos E. M., Santos-Lima R., Sanuy A., Sarkar S., Saturni F. G., Sawangwit U., Schussler F., Schwanke U., Sciacca E., Scuderi S., Seglar-Arroyo M., Sergijenko O., Servillat M., Seweryn K., Shalchi A., Sharma P., Shellard R. C., Siejkowski H., Silk J., Siqueira C., Sliusar V, Sokolenko A., Sol H., Spencer S., Stamerra A., Stanic S., Starling R., Stolarczyk T., Straumann U., Striskovic J., Suda Y., Suomijarvi T., Swierk P., Tavecchio F., Taylor L., Tejedor L. A., Teshima M., Testa V, Tibaldo L., Todero Peixoto C. J., Tokanai F., Tonev D., Tosti G., Tosti L., Tothill N., Truzzi S., Travnicek P., Vagelli V., Vallage B., Vallania P., van Eldik C., Vandenbroucke J., Varner G. S., Vassiliev V., Vazquez Acosta M., Vecchi M., Ventura S., Vercellone S., Vergani S., Verna G., Viana A., Vigorito C. F., Vink J., Vitale V., Vorobiov S., Vovk I, Vuillaume T., Wagner S. J., Walter R., Watson J., Weniger C., White R., White M., Wiemann R., Wierzcholska A., Will M., Williams D. A., Wischnewski R., Yanagita S., Yang L., Yoshikoshi T., Zacharias M., Zaharijas G., Zakaria A. A., Zampieri L., Zanin R., Zaric D., Zavrtanik M., Zavrtanik D., Zdziarski A. A., Zech A., Zechlin H., Zhdanov V. I, Zivec M.

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS Vol. 2021 ( 1 ) 2021.1

Technical and scientific performance of the prototype Schwarzschild-Couder Telescope for CTA

Adams C.B., Ambrosi G., Ambrosio M., Aramo C., Batista P.I., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolontà C., Bose R., Brill A., Brown A.M., Buckley J.H., Canestrari R., Capasso M., Caprai M., Covault C.E., Depaoli D., Di Venere L., Errando M., Fegan S., Feng Q., Fiandrini E., Furniss A., Gent A., Giglietto N., Giordano F., Giro E., Halliday R., Hervet O., Holder J., Humensky T.B., Incardona S., Ionica M., Jin W., Kieda D., Licciulli F., Loporchio S., Marsella G., Masone V., Meagher K., Meures T., Mode B.A.W., Mognet S.A.I., Mukherjee R., Nieto D., Okumura A., Otte N., Pantaleo F.R., Paoletti R., Pareschi G., Di Pierro F., Pueschel E., Ribeiro D., Riitano L., Roache E., Ross D., Rousselle J., Rugliancich A., Santander M., Shang R., Stiaccini L., Tajima H., Taylor L.P., Tosti L., Tovmassian G., Tripodo G., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V.V., Watson J.J., White R., Williams D.A., Yu P., Zink A.

Proceedings of SPIE - The International Society for Optical Engineering Vol. 11820 2021

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Proceedings of SPIE - The International Society for Optical Engineering

The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma rays. One candidate design for CTA’s medium-sized telescopes consists of the Schwarzschild-Couder Telescope (SCT), featuring innovative dual-mirror optics. The SCT project has built and is currently operating a 9.7-m prototype SCT (pSCT) at the Fred Lawrence Whipple Observatory (FLWO); such optical design enables the use of a compact camera with state-of-the art silicon photomultiplier detectors. A partially-equipped camera has recently successfully detected the Crab Nebula with a statistical significance of 8.6 standard deviations. A funded upgrade of the pSCT focal plane sensors and electronics is currently ongoing, which will bring the total number of channels from 1600 to 11328 and the telescope field of view from about 2.7◦ to 8◦. In this work, we will describe the technical and scientific performance of the pSCT.

DOI： 10.1117/12.2594580

Status of the development of NUV SiPMs for INFN optical modules for the SCT medium sized telescope proposed for the CTA observatory

Adams C., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolonta C., Bose R., Brill A., Buckley J. H., Caprai M., Covault C. E., Di Venere L., Feng Q., Fiandrini E., Gent A., Giglietto N., Giordano F., Halliday R., Hervet O., Hughes G., Humensky T. B., Ionica M., Jin W., Kaaret P., Kieda D., Kim B., Licciulli F., Loporchio S., Masone V., Meures T., Mode B. A. W., Mukherjeek R., Okumura A., Otte N., Pantaleo F. R., Paoletti R., Petrashyk A., Powell J., Powell K., Riberio D., Rouselle J., Rugliancich A., Santander M., Shang R., Stevenson B., Stiaccini L., Taylor L. P., Tosti L., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V., Wilcox P., Williams D. A.

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 982 2020.12

Study of the Cosmic Rays and Interstellar Medium in Local HI Clouds Using Fermi-LAT Gamma-Ray Observations

Mizuno T., Abdollahi S., Fukui Y., Hayashi K., Koyama T., Okumura A., Tajima H., Yamamoto H.

ASTROPHYSICAL JOURNAL Vol. 890 ( 2 ) 2020.2

Front-end electronics of the Compact High Energy Camera

Leach S. A., Lapington J. S., Ross D., Thornhill J., Duffy C., Funk S., Zink A., Jankowsky D., White R., Zorn J., Tibaldo L., Varner G., Okumura A., Tajima H., Watson J.

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 952 2020.2

Alignment of the optical system of the 9.7-m prototype Schwarzchild-Coulder Telescope

Adams C.

Proceedings of SPIE - The International Society for Optical Engineering Vol. 11445 2020

Verification of the Optical System of the 9.7-m Prototype Schwarzschild-Couder Telescope

Adams C., Alfaro R., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolonta C., Bose R., Brill A., Buckley J. H., Byrum K., Cameron R. A., Capasso M., Caprai M., Covault C. E., Di Venere L., Fegan S., Feng Q., Fiandrini E., Furniss A., Garczarczyk M., Garfias F., Gent A., Giglietto N., Giordano F., Gonzalez M. M., Halliday R., Hervet O., Hughes G., Humensky T. B., Ionica M., Iriarte A., Jin W., Kaarat P., Kieda D., Kim B., Licciulli F., Limon M., Loporchio S., Masone V, Meures T., Mode B. A. W., Mukherjee R., Nieto D., Okumura A., Otte N., La Palombara N., Pantaleo F. R., Paoletti R., Pareschi G., Petrashyk A., Powell J., Powell K., Ribeiro D., Roache E., Rousselle J., Rugliancich A., Ruiz-Diaz-Soto J., Santander M., Schlenstedt S., Scuderi S., Shang R., Sironi G., Stevenson B., Stiaccini L., Taylor L. P., Tosti L., Tovmassian G., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V. V., Wakely S. P., Wilcox P., Williams D. A., Yu P.

OPTICAL SYSTEM ALIGNMENT, TOLERANCING, AND VERIFICATION XIII Vol. 11488 2020

Design and production of segment mirrors for the Large-Sized Telescopes of the Cherenkov Telescope Array

Inada T.

Proceedings of SPIE - The International Society for Optical Engineering Vol. 11451 2020

Calibration and performance of the readout system based on switched capacitor arrays for the Large-Sized Telescope of the Cherenkov Telescope Array

Seiya Nozaki, Kyosuke Awai, Aya Bamba, Juan Abel Barrio, Maria Isabel Bernardos, Oscar Blanch, Joan Boix, Franca Cassol, Yuuki Choushi, Carlos Delgado, Carlos Diaz, Nadia Fouque, Lluis Freixas, Pawel Gliwny, Shuichi Gunji, Daniela Hadasch, Dirk Hoffmann, Julien Houles, Yusuke Inome, Yuki Iwamura, Lea Jouvin, Hideaki Katagiri, Kiomei Kawamura, Daniel Kerszberg, Yusuke Konno, Hidetoshi Kubo, Junko Kushida, Yukiho Kobayashi, Ruben Lopez, Gustavo Martinez, Shu Masuda, Daniel Mazin, Abelardo Moralejo, Elena Moretti, Tsutomu Nagayoshi, Takeshi Nakamori, Kyoshi Nishijima, Yuto Nogami, Leyre Nogués, Hideyuki Ohoka, Tomohiko Oka, Nao Okazaki, Akira Okumura, Reiko Orito, Jean-Luc Panazol, Riccardo Paoletti, Cristobal Pio, Miguel Polo, Julie Prast, Takayuki Saito, Shunsuke Sakurai, Julian Sitarek, Yuji Sunada, Megumi Suzuki, Mitsunari Takahashi, Kenji Tamura, Manobu Tanaka, Luis Angel Tejedor, Yukikatsu Terada, Masahiro Teshima, Yusuke Tsukamoto, Tokonatsu Yamamoto

Ground-based and Airborne Instrumentation for Astronomy VIII Vol. 11447 page： 114470H 2020

CTA report 161: Cross-calibration of the CTA-LST1 and the MAGIC telescopes

Ohtani Y., Orito R., Kajiwara Y., Katagiri H., Kushida J., Kubo H., Gunji S., Kobayashi Y., Saito T., Sakaki N., Sakurai S., Abe H., Zenin A., Takahashi Mari, Takahashi Mitsunari, Tateishi D., Chikawa M., Choshi Y., Teshima M., Nakamori T., Nabatame Y., Nishijima K., Inada T., Nogami Y., Nozaki S., Nomura R., Harada Y., Fukami S., Fujihara C., Furuta T., Yamamoto T., Yoshikoshi T., Yoshida T., Imagawa K., for the CTA-Japan, Iwamura Y., Ohishi M., Oka T., Ogata T., Okumura A.

Meeting Abstracts of the Physical Society of Japan Vol. 75 page： 441 - 441 2020

CTA Report 162: CTA-LST1 camera calibration

Kobayashi Y., Oka T., Okazaki N., Ogata T., Okumura A., Orito R., Kajiwara Y., Katagiri H., Kushida J., Kubo H., Gunji S., Abe H., Saito T., Sakaki N., Sakurai S., Suzuki M., Sunada Y., Zenin A., Takahashi Mari, Takahashi Mitsunari, Tateishi D., Tanaka M., Inada T., Tamura K., Chikawa M., Choshi Y., Teshima M., Terada Y., Tokanai F., Nakamori T., Nabatame Y., Nishijima K., Nogami Y., Inome Y., Nozaki S., Noda K., Nomura R., Hadasch D., Harada Y., Fukami S., Fujihara C., Furuta T., Mazin D., Yamamoto T., Imagawa K., Yoshikoshi T., Yoshida T., for the CTA-Japan Consortium, Iwamura Y., Ohishi M., Ohoka H., Ohtani Y.

Meeting Abstracts of the Physical Society of Japan Vol. 75 page： 471 - 471 2020

CTA Report 160: Status of the mono analysis for the LST proposed for CTA

Nozaki S., Okumura A., Orito R., Kajiwara Y., Katagiri H., Kushida J., Kubo H., Gunji S., Kobayashi S., Saito T., Sakaki N., Abe H., Sakurai S., Zenin A., Takahashi Mari, Takahashi Mitsunari, Tateishi D., Chikawa M., Choshi Y., Teshima M., Nakamori T., Nabatame Y., Inada T., Nishijima K., Nogami Y., Nomura R., Harada Y., Fukami S., Fujihara C., Furuta T., Yamamoto T., Yoshikoshi T., Yoshida T., Imagawa K., the CTA-Japan Consortium, Iwamura Y., Ohishi M., Ohtani Y., Oka T., Ogata T.

Meeting Abstracts of the Physical Society of Japan Vol. 75 page： 440 - 440 2020

CTA Report 159: General Report

Kubo Hidetoshi, Teshima Masahiro, Totani Tomonori, Asano Katsuaki, Abe Hyuga, Awai Kyosuke, Ioka Kunihito, Ishio Kazuma, Ishizaki Wataru, Inada Tomohiro, Inoue Susumu, Inoue Tsuyoshi, Inoue Yoshiyuki, Inome Yusuke, Imagawa Kaname, Iwamura Yuki, Warren Donald, Uchiyama Yasunobu, Ohishi Michiko, Ohoka Hideyuki, Ohtani Yoshiki, Ohira Yutaka, Oka Tomohiko, Okazaki Nao, Ogata Tomoyuki, Okumura Akira, Obara Kotaro, Orito Reiko, Kagaya Mika, Kajiwara Yuki, Kataoka Jun, Katagiri Hideaki, Katsukura Daisuke, Katsuda Satoru, Khalikov Emil, Kawashima Shotaro, Kawanaka Norita, Kawamura Kiomei, Kisaka Shota, Cui Xiaohong, Kushida Junko, Kuroda Yusuke, Gunji Shuichi, Kohri Kazunori, Kobayashi Yukiho, Kong Albert K. H., Saito Takayuki, Sakaki Naoto, Sakurai Shunsuke, Sano Hidetoshi, Sawada Makoto, Shibata Toru, Dzhatdoev Timur, Suzuki Megumi, Suzuki Hiromasa, Suda Yusuke, Strzys Marcel, Sunada Yuji, Zenin Anatolii, Takata Jumpei, Takahashi Mari, Takahashi Keitaro, Takahashi Hiromitsu, Takahashi Mitsunari, Tajima Hiroyasu, Tachihara Kengo, Tateishi Dai, Tanaka Shuta, Tanaka Takaaki, Tanaka Manobu, Tam Thomas P. H., Tamura Kenji, Cheng K. S., Chikawa Michiyuki, Choushi Yuuki, Tsukamoto Yusuke, Tsujimoto Shimpei, Tsuru Takeshi, Tian Wenwu, Terada Yukikatsu, Toma Kenji, Tokanai Fuyuki, Naito Tsuguya, Nagataki Shigehiro, Nakamura Yuki, Nakamori Takeshi, Nakayama Kazunori, Nabatame Yasuyuki, Nishijima Kyoshi, Nogami Yuto, Nozaki Seiya, Noda Koji, Nomura Ryosuke, Barkov Maxim, Hadasch Daniela, Hayakawa Takahiro, Hayashi Kohei, Hayashi Katsuhiro, Hayashida Masaaki, Hara Satoshi, Harada Yoshiki, Bamba Aya, Hiroshima Nagisa, Hirotani Kouichi, Hui David C. Y., Ferrand Gilles, Fukazawa Yasushi, Fukami Satoshi, Fukui Yasuo, Fujikawa Yui, Fujita Yutaka, Fujihara Chikako, Furuta Tomoya, He Haoning, Vovk Ievgen, Majumdar Pratik, Mazin Daniel, Matsumoto Hironori, Mizuno Tsunefumi, Muraishi Hiroshi, Murase Kohta, Mori Koji, Yanagita Shohei, Yamazaki Ryo, Yamane Yumiko, Yamamoto Tokonatsu, Yamamoto Hiroaki, Yoshikoshi Takanori, Yoshida Atsumasa, Yoshida Tatsuo, Lee Shiu-Hang (Herman)

Meeting Abstracts of the Physical Society of Japan Vol. 75.1 page： 439 - 439 2020

Fermi-LAT γ-Ray Study of the Interstellar Medium and Cosmic Rays in the Chamaeleon Molecular Cloud Complex: A Look at the Dark Gas as Optically Thick H i Reviewed

H. Sano, Katsuhiro Hayashi, Tsunefumi Mizuno, Yasuo Fukui, Ryuji Okamoto, Hiroaki Yamamoto, Naoya Hidaka, Akira Okumura, Hiroyasu Tajima, Hidetoshi Sano

The Astrophysical Journal Vol. 884 ( 2 ) 2019.10

Publishing type：Research paper (scientific journal)

We report a Fermi-LAT $\gamma$-ray analysis for the Chamaeleon 
molecular-cloud complex using a total column density (NH) model based on the 
dust optical depth at 353 GHz ($\tau_{353}$) with the Planck thermal dust 
emission model. Gamma rays with energy from 250 MeV to 100 GeV are fitted with 
the NH model as a function of $\tau_{353}$, NH $\propto$ 
$\tau_{353}^{1/\alpha}$ ($\alpha$ $\geq$ 1.0), to explicitly take into account 
a possible nonlinear $\tau_{353}$/NH ratio. We found that a nonlinear relation, 
$\alpha$$\sim$1.4, gives the best fit to the $\gamma$-ray data. This nonlinear 
relation may indicate dust evolution effects across the different gas phases. 
Using the best-fit NH model, we derived the CO-to-H2 conversion factor (XCO) 
and gas mass, taking into account uncertainties of the NH model. The value of 
XCO is found to be (0.63-0.76) $\times$10$^{20}$ cm$^{-2}$ K$^{-1}$ km$^{-1}$ 
s, which is consistent with that of a recent $\gamma$-ray study of the 
Chamaeleon region. The total gas mass is estimated to be (6.0-7.3) $\times$ 
10$^{4}$ Msun, of which the mass of additional gas not traced by standard HI or 
CO line surveys is 20-40%. The additional gas amounts to 30-60% of the gas mass 
estimated in the case of optically thin HI and has 5-7 times greater mass than 
the molecular gas traced by CO. Possible origins of the additional gas are 
discussed based on scenarios of optically thick HI and CO-dark H2. We also 
derived the $\gamma$-ray emissivity spectrum, which is consistent with the 
local HI emissivity derived from LAT data within the systematic uncertainty of 
$\sim$20%

DOI： 10.3847/1538-4357/ab4351

Monte Carlo studies for the optimisation of the Cherenkov Telescope Array layout

Acharyya A

Astroparticle Physics Vol. 111 page： 35 - 53 2019.9

Characterization of SiPM Optical Crosstalk and its Dependence on the Protection-Window Thickness

Nakamura, Yuki, Okumura, Akira, Tajima, Hiroyasu, Yamane, Nobuhito, Zenin, Anatolii

2019.9

Language：English Publishing type：Research paper (scientific journal) Publisher：arXiv e-prints

Owing to their high photon detection efficiency, compactness, and low operating voltage, silicon photomultipliers (SiPMs) have found widespread application in many fields, including medical imaging, particle physics, and high-energy astrophysics. However, the so-called optical crosstalk (OCT) phenomenon of SiPMs is a major drawback to their adoption. Secondary infrared photons are emitted inside the silicon substrate spontaneously after the avalanche process caused by the primary incident photons, and they can be detected by the surrounding photodiodes. As a result large output pulses that are equivalent to multiple photoelectrons are observed with a certain probability (OCT rate), even for single-photon events, making the charge resolution worse and increasing the rate of accidental triggers by single-photon events in applications such as atmospheric Cherenkov telescopes. In our previous study, we found that the OCT rates of single-channel SiPMs was dependent on the thickness of their protection resin window, which may be explained by photon propagation inside the resin. In the present study, we measured the OCT rate of a multichannel SiPM and those of neighboring channels caused by photon propagation. Both OCT rates were found to be dependent on the protection-window thickness. We report our OCT measurements of a multichannel SiPM and comparisons with a ray-tracing simulation....

Development of a UV-transparent Lens Array for Enlarging the Effective Area of Multichannel SiPMs

Okumura, Akira, Asano, Akira, Furuta, Kazuhiro, Hidaka, Naoya, Nakamura, Yuki, Tajima, Hiroyasu, Zenin, Anatolii

2019.8

Language：English Publishing type：Research paper (scientific journal) Publisher：arXiv e-prints

We developed a UV-transparent lens array that can increase the photon detection efficiency of a silicon photomultiplier (SiPM) array comprising of 64 pixels ($3\times3$ mm$^2$ each) and 0.2-mm gaps. Through the plano-convex spherical lens on each $3.2\times3.2$ mm$^2$ region, we showed that the loss of photon detection efficiency due to the pixel gaps could be recovered as the incident photons get concentrated on the sensitive regions of the SiPM array. By using a prototype lens array, we achieved approximately 10%-30% relative increase in photon detection efficiency in our target angles of incidence of 30-60 deg....

Using Muon Rings for the Calibration of the Cherenkov Telescope Array: A Systematic Review of the Method and Its Potential Accuracy

Gaug M., Fegan S., Mitchell A. M. W., Maccarone M. C., Mineo T., Okumura A.

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES Vol. 243 ( 1 ) 2019.7

Camera design and performance of the prototype schwarzschild-couder telescope for the Cherenkov Telescope Array

Adams C.

Proceedings of Science Vol. 358 2019

Using muon rings for the optical throughput calibration of the Cherenkov Telescope array

Gaug M.

Proceedings of Science Vol. 358 2019

Upgrading the prototype Schwarzschild-Couder telescope camera to a wide-field, high-resolution instrument

Adams C.

Proceedings of Science Vol. 358 2019

The calibration of the first large-sized telescope of the Cherenkov telescope array

Sakurai S.

Proceedings of Science Vol. 358 2019

Prototype schwarzschild-couder telescope for the cherenkov telescope array: Commissioning status of the optical system

Adams C.

Proceedings of Science Vol. 358 2019

Introduction to CTA Science

Acharya B. S., Agudo I., Al Samarai I., Alfaro R., Alfaro J., Alispach C., Batista R. Alves, Amans J. -P., Amato E., Ambrosi G., Antolini E., Antonelli L. A., Aramo C., Araya M., Armstrong T., Arqueros F., Arrabito L., Asano K., Ashley M., Backes M., Balazs C., Balbo M., Ballester O., Ballet J., Bamba A., Barkov M., Barres de Almeida U., Barrio J. A., Bastieri D., Becherini Y., Belfiore A., Benbow W., Berge D., Bernardini E., Bernardini M. G., Bernardos M., Bernloehr K., Bertucci B., Biasuzzi B., Bigongiari C., Biland A., Bissaldi E., Biteau J., Blanch O., Blazek J., Boisson C., Bolmont J., Bonanno G., Bonardi A., Bonavolonta C., Bonnoli G., Bosnjak Z., Bottcher M., Braiding C., Bregeon J., Brill A., Brown A. M., Brun P., Brunetti G., Buanes T., Buckley J., Bugaev V., Buehler R., Bulgarelli A., Bulik T., Burton M., Burtovoi A., Busetto G., Canestrari R., Capalbi M., Capitanio F., Caproni A., Caraveo P., Cardenas V., Carlile C., Carosi R., Carquin E., Carr J., Casanova S., Cascone E., Catalani F., Catalano O., Cauz D., Cerruti M., Chadwick P., Chaty S., Chaves R. C. G., Chen A., Chen X., Chernyakova M., Chikawa M., Christov A., Chudoba J., Cieslar M., Coco V., Colafrancesco S., Colin P., Conforti V., Connaughton V., Conrad J., Contreras J. L., Cortina J., Costa A., Costantini H., Cotter G., Covino S., Crocker R., Cuadra J., Cuevas O., Cumani P., D'Ai A., D'Ammando F., D'Avanzo P., D'Urso D., Daniel M., Davids I., Dawson B., Dazzi F., De Angelis A., de Cassia dos Anjos R., De Cesare G., De Franco A., De Gouveia Dal Pino E. M., de la Calle I., Lopez R. de los Reyes, De Lotto B., De Luca A., De Lucia M., de Naurois M., de Ona Wilhelmi E., De Palma F., De Persio F., de Souza V., Deil C., Del Santo M., Delgado C., della Volpe D., Di Girolamo T., Di Pierro F., Di Venere L., Diaz C., Dib C., Diebold S., Djannati-Atai A., Dominguez A., Prester D. Dominis, Dorner D., Doro M., Drass H., Dravins D., Dubus G., Dwarkadas V. V., Ebr J., Eckner C., Egberts K., Einecke S., Ekoume T. R. N., Elsaesser D., Ernenwein J. -P., Espinoza C., Evoli C., Fairbairn M., Falceta-Goncalves D., Falcone A., Farnier C., Fasola G., Fedorova E., Fegan S., Fernandez-Alonso M., Fernandez-Barral A., Ferrand G., Fesquet M., Filipovic M., Fioretti V., Fontaine G., Fornasa M., Fortson L., Freixas Coromina L., Fruck C., Fujita Y., Fukazawa Y., Funk S., Fuessling M., Gabici S., Gadola A., Gallant Y., Garcia B., Garcia Lopez R., Garczarczyk M., Gaskins J., Gasparetto T., Gaug M., Gerard L., Giavitto G., Giglietto N., Giommi P., Giordano F., Giro E., Giroletti M., Giuliani A., Glicenstein J. -F., Gnatyk R., Godinovic N., Goldoni P., Gomez-Vargas G., Gonzalez M. M., Gonzalez J. M., Gotz D., Graham J., Grandi P., Granot J., Green A. J., Greenshaw T., Griffiths S., Gunji S., Hadasch D., Hara S., Hardcastle M. J., Hassan T., Hayashi K., Hayashida M., Heller M., Helo J. C., Hermann G., Hinton J., Hnatyk B., Hofmann W., Holder J., Horan D., Horandel J., Horns D., Horvath P., Hovatta T., Hrabovsky M., Hrupec D., Humensky T. B., Huetten M., Iarlori M., Inada T., Inome Y., Inoue S., Inoue T., Inoue Y., Iocco F., Ioka K., Iori M., Ishio K., Iwamura Y., Jamrozy M., Janecek P., Jankowsky D., Jean P., Jung-Richardt I., Jurysek J., Kaaret P., Karkar S., Katagiri H., Katz U., Kawanaka N., Kazanas D., Khelifi B., Kieda D. B., Kimeswenger S., Kimura S., Kisaka S., Knapp J., Knodlseder J., Koch B., Kohri K., Komin N., Kosack K., Kraus M., Krause M., Krauss F., Kubo H., Mezek G. Kukec, Kuroda H., Kushida J., La Palombara N., Lamanna G., Lang R. G., Lapington J., Le Blanc O., Leach S., Lees J. -P., Lefaucheur J., Leigui de Oliveira M. A., Lenain J. -P., Lico R., Limon M., Lindfors E., Lohse T., Lombardi S., Longo F., Lopez M., Lopez-Coto R., Lu C. -C., Lucarelli F., Luque-Escamilla P. L., Lyard E., Maccarone M. C., Maier G., Majumdar P., Malaguti G., Mandat D., Maneva G., Manganaro M., Mangano S., Marcowith A., Marin J., Markoff S., Marti J., Martin P., Martinez M., Martinez G., Masetti N., Masuda S., Maurin G., Maxted N., Mazin D., Medina C., Melandri A., Mereghetti S., Meyer M., Minaya I. A., Mirabal N., Mirzoyan R., Mitchell A., Mizuno T., Moderski R., Mohammed M., Mohrmann L., Montaruli T., Moralejo A., Morcuende-Parrilla D., Mori K., Morlino G., Morris P., Morselli A., Moulin E., Mukherjee R., Mundell C., Murach T., Muraishi H., Murase K., Nagai A., Nagataki S., Nagayoshi T., Naito T., Nakamori T., Nakamura Y., Niemiec J., Nieto D., Nikolajuk M., Nishijima K., Noda K., Nosek D., Novosyadlyj B., Nozaki S., O'Brien P., Oakes L., Ohira Y., Ohishi M., Ohm S., Okazaki N., Okumura A., Ong R. A., Orienti M., Orito R., Osborne J. P., Ostrowski M., Otte N., Oya I., Padovani M., Paizis A., Palatiello M., Palatka M., Paoletti R., Paredes J. M., Pareschi G., Parsons R. D., Pe'er A., Pech M., Pedaletti G., Perri M., Persic M., Petrashyk A., Petrucci P., Petruk O., Peyaud B., Pfeifer M., Piano G., Pisarski A., Pita S., Pohl M., Polo M., Pozo D., Prandini E., Prast J., Principe G., Prokhorov D., Prokoph H., Prouza M., Puehlhofer G., Punch M., Puerckhauer S., Queiroz F., Quirrenbach A., Raino S., Razzaque S., Reimer O., Reimer A., Reisenegger A., Renaud M., Rezaeian A. H., Rhode W., Ribeiro D., Ribo M., Richtler T., Rico J., Rieger F., Riquelme M., Rivoire S., Rizi V., Rodriguez J., Fernandez G. Rodriguez, Rodriguez Vazquez J. J., Rojas G., Romano P., Romeo G., Rosado J., Rovero A. C., Rowell G., Rudak B., Rugliancich A., Rulten C., Sadeh I., Safi-Harb S., Saito T., Sakaki N., Sakurai S., Salina G., Sanchez-Conde M., Sandaker H., Sandoval A., Sangiorgi P., Sanguillon M., Sano H., Santander M., Sarkar S., Satalecka K., Saturni F. G., Schioppa E. J., Schlenstedt S., Schneider M., Schoorlemmer H., Schovanek P., Schulz A., Schussler F., Schwanke U., Sciacca E., Scuderi S., Seitenzahl I., Semikoz D., Sergijenko O., Servillat M., Shalchi A., Shellard R. C., Sidoli L., Siejkowski H., Sillanpaa A., Sironi G., Sitarek J., Sliusar V., Slowikowska A., Sol H., Stamerra A., Stanic S., Starling R., Stawarz L., Stefanik S., Stephan M., Stolarczyk T., Stratta G., Straumann U., Suomijarvi T., Supanitsky A. D., Tagliaferri G., Tajima H., Tavani M., Tavecchio F., Tavernet J. -P., Tayabaly K., Tejedor L. A., Temnikov P., Terada Y., Terrier R., Terzic T., Teshima M., Testa V., Thoudam S., Tian W., Tibaldo L., Tluczykont M., Todero Peixoto C. J., Tokanai F., Tomastik J., Tonev D., Tornikoski M., Torres D. F., Torresi E., Tosti G., Tothill N., Tovmassian G., Travnicek P., Trichard C., Trifoglio M., Pujadas I. Troyano, Tsujimoto S., Umana G., Vagelli V., Vagnetti F., Valentino M., Vallania P., Valore L., van Eldik C., Vandenbroucke J., Varner G. S., Vasileiadis G., Vassiliev V., Vazquez Acosta M., Vecchi M., Vega A., Vercellone S., Veres P., Vergani S., Verzi V., Vettolani G. P., Viana A., Vigorito C., Villanueva J., Voelk H., Vollhardt A., Vorobiov S., Vrastil M., Vuillaume T., Wagner S. J., Wagner R., Walter R., Ward J. E., Warren D., Watson J. J., Werner F., White M., White R., Wierzcholska A., Wilcox P., Will M., Williams D. A., Wischnewski R., Wood M., Yamamoto T., Yamazaki R., Yanagita S., Yang L., Yoshida T., Yoshiike S., Yoshikoshi T., Zacharias M., Zaharijas G., Zampieri L., Zandanel F., Zanin R., Zavrtanik M., Zavrtanik D., Zdziarski A. A., Zech A., Zechlin H., Zhdanov V. I., Ziegler A., Zorn J.

SCIENCE WITH THE CHERENKOV TELESCOPE ARRAY page： 1 - + 2019

Development and operations of INFN optical modules for the SCT telescope camera proposed for the Cherenkov Telescope Array Observatory

Adams C.

Proceedings of Science Vol. 358 2019

Characterization and assembly of near-ultraviolet SiPMs for the Schwarzschild-Couder medium-size telescope proposed for the CTA Observatory

Adams C., Ambrosi G., Ambrosio M., Aramo C., Benbow W., Bertucci B., Bissaldi E., Bitossi M., Boiano A., Bonavolonta C., Bose R., Brill A., Buckley J. H., Caprai M., Covault C. E., Di Venere L., Feng Q., Fiandrini E., Gent A., Giglietto N., Giordano F., Halliday R., Hervet O., Hughes G., Humensky T. B., Ionica M., Jin W., Kaaret P., Kieda D., Kim B., Licciulli F., Loporchio S., Masone V., Meures T., Mode B. A. W., Mukherjee R., Okumura A., Otte N., Pantaleo F. R., Paoletti R., Petrashyk A., Powell J., Powell K., Ribeiro D., Rousselle J., Rugliancich A., Santander M., Shang R., Stevenson B., Stiaccini L., Taylor L. P., Tosti L., Vagelli V., Valentino M., Vandenbroucke J., Vassiliev V., Wilcox P., Williams D. A.

HARD X-RAY, GAMMA-RAY, AND NEUTRON DETECTOR PHYSICS XXI Vol. 11114 2019

CTA Report 156: Evaluation of effect of uncertainty in hadronic interaction models on the estimation of CTA sensitivity

Ohishi Michiko, Arbeletche Luan, Souza Vitor de, Maier Gernot, Bernloehr Konrad, Moralejo Abelardo, Bregeon Johan, Arrabito Luisa, Yoshikoshi Takanori, Iwamura Yuki, Ohtani Yoshiki, Ogata Tomoyuki, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kushida Junko, Gunji Shuichi, Kobayashi Yukiho, Saito Takayuki, Sakaki Naoto, Sakurai Shunsuke, Zenin Anatolii, Chikawa Michiyuki, Nakamori Takeshi, Nishijima Kyoshi, Miura Chika, Nozaki Seiya, Fukami Satoshi, Fujihara Chikako, Furuta Tomoya, Yoshida Tatsuo, the CTA-Japan Consortium

Meeting Abstracts of the Physical Society of Japan Vol. 74.2 ( 0 ) page： 359 - 359 2019

CTA Report 148: A Monte Carlo simulation study using muon events of Large Size Telescope

Ri Ken, Gunji Shuichi, Saito Takayuki, Sakaki Naoto, Sasai Yoshinori, Takahashi Tomoya, Taneda Yuki, Nakamori Takeshi, Nishijima Kyoshi, Miura Chika, Yoshikoshi Takanori, Fujihara Chikako, Yoshida Tatsuo, Zenin Anatolii, the CTA-Japan Consortium, Chikawa Michiyuki, Ohishi Michiko, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko

Meeting Abstracts of the Physical Society of Japan Vol. 74 page： 557 - 557 2019

CTA Report 157: Measurement of timing response performance of photomultiplier tube used for CTA large sized telescope

Sunada Yuji, Katagiri Hideaki, Kushida Junko, Kubo Hidetoshi, Gunji Shuichi, Kobayashi Yukiho, Saito Takayuki, Sakurai Shunsuke, Suzuki Megumi, Takahashi Mitsunari, Tanaka Manobu, Inome Yusuke, Tamura Kenji, Choushi Yuuki, Teshima Masahiro, Terada Yukikatsu, Tokanai Fuyuki, Nakamori Takeshi, Nagayoshi Tsutomu, Nishijima Kyoshi, Nogami Yuto, Nozaki Seiya, Iwamura Yuki, Noda Koji, Hadasch Daniela, Hayashida Masaaki, Bamba Aya, Hirako Joe, Furuta Tomoya, Mazin Daniel, Masuda Shu, Yamamoto Tokonatsu, Yoshida Tatsuo, Ohoka Hideyuki, Ikeno Masahiro, Uchida Tomohisa, Oka Tomohiko, Okazaki Nao, Okumura Akira, Orito Reiko, Kajiwara Yuki

Meeting Abstracts of the Physical Society of Japan Vol. 74 page： 360 - 360 2019

CTA Report 150: Commissioning test of the focal plane camera of the first CTA Large-Sized Telescope.

Nozaki S., Kajiwara Y., Katagiri H., Kushida J., Kimura S., Kubo H., Gunji S., Koyama S., Saito T., Sakurai S., Sawada M., Inada T., Suzuki M., Sunada Y., Takahashi M., Takahara H., Tanaka M., Tamura K., Choushi Y., Tujimoto S., Teshima M., Terada Y., Inome Y., Tokanai F., Nakamori T., Nagayoshi T., Nishijima K., Nishiyama G., Noda K., Hayashida M., Bamba A., Hirako J., Fukami S., Iwamura Y., Furuta T., Masuda S., Yamamoto T., Yoshida T., Hadasch Daniela, Mazin Daniel, the CTA-Japan consortium, Ikeno M., Uchida T., Ohoka H., Okazaki N., Oka T., Okumura A., Orito R.

Meeting Abstracts of the Physical Society of Japan Vol. 74 page： 559 - 559 2019

CTA Report 149: Development of analysis software for CTA LST-1

Iwamura Yuki, Kubo Hidetoshi, Gunji Shuichi, Kobayashi Yukiho, Saito Takayuki, Sakaki Naoto, Sakurai Shunsuke, Sasai Yoshinori, Sunada Yuji, Takahashi Tomoya, Taneda Yuki, Inada Tomohiro, Chikawa Michiyuki, Choushi Yuuki, Teshima Masahiro, Terada Yukikatsu, Nakamori Takeshi, Nishijima Kyoshi, Nozaki Seiya, Noda Koji, Hayashida Masaaki, Hiroshima Nagisa, Ohishi Michiko, Fukami Satoshi, Fujihara Chikako, Miura Chika, Yamamoto Tokonatsu, Yoshikoshi Takanori, Yoshida Tatsuo, Ri Ken, Zenin Anatolii, the CTA-Japan Consortium, Ohtani Yoshiki, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko

Meeting Abstracts of the Physical Society of Japan Vol. 74 page： 558 - 558 2019

Science with the Cherenkov Telescope Array

Cherenkov Telescope Array Consortium, Acharya, B. S., Agudo, I., Al Samarai, I., Alfaro, R., Alfaro, J., Alispach, C., Alves Batista, R., Amans, J. -P., Amato, E., Ambrosi, G., Antolini, E., Antonelli, L. A., Aramo, C., Araya, M., Armstrong, T., Arqueros, F., Arrabito, L., Asano, K., Ashley, M., Backes, M., Balazs, C., Balbo, M., Ballester, O., Ballet, J., Bamba, A., Barkov, M., Barres de Almeida, U., Barrio, J. A., Bastieri, D., Becherini, Y., Belfiore, A., Benbow, W., Berge, D., Bernardini, E., Bernardini, M. G., Bernardos, M., Bernlöhr, K., Bertucci, B., Biasuzzi, B., Bigongiari, C., Biland, A., Bissaldi, E., Biteau, J., Blanch, O., Blazek, J., Boisson, C., Bolmont, J., Bonanno, G., Bonardi, A., Bonavolontà, C., Bonnoli, G., Bosnjak, Z., Böttcher, M., Braiding, C., Bregeon, J., Brill, A., Brown, A. M., Brun, P., Brunetti, G., Buanes, T., Buckley, J., Bugaev, V., Bühler, R., Bulgarelli, A., Bulik, T., Burton, M., Burtovoi, A., Busetto, G., Canestrari, R., Capalbi, M., Capitanio, F., Caproni, A., Caraveo, P., Cárdenas, V., Carlile, C., Carosi, R., Carquín, E., Carr, J., Casanova, S., Cascone, E., Catalani, F., Catalano, O., Cauz, D., Cerruti, M., Chadwick, P., Chaty, S., Chaves, R. C. G., Chen, A., Chen, X., Chernyakova, M., Chikawa, M., Christov, A., Chudoba, J., Cieślar, M., Coco, V., Colafrancesco, S., Colin, P., Conforti, V., Connaughton, V., Conrad, J., Contreras, J. L., Cortina, J., Costa, A., Costantini, H., Cotter, G., Covino, S., Crocker, R., Cuadra, J., Cuevas, O., Cumani, P., D'Aì, A., D'Ammando, F., D'Avanzo, P., D'Urso, D., Daniel, M., Davids, I., Dawson, B., Dazzi, F., De Angelis, A., de Cássia dos Anjos, R., De Cesare, G., De Franco, A., de Gouveia Dal Pino, E. M., de la Calle, I., de los Reyes Lopez, R., De Lotto, B., De Luca, A., De Lucia, M., de Naurois, M., de Oña Wilhelmi, E., De Palma, F., De Persio, F., de Souza, V., Deil, C., Del Santo, M., Delgado, C., della Volpe, D., Di Girolamo, T., Di Pierro, F., Di Venere, L., Díaz, C., Dib, C., Diebold, S., Djannati-Ataï, A., Domínguez, A., Dominis Prester, D., Dorner, D., Doro, M., Drass, H., Dravins, D., Dubus, G., Dwarkadas, V. V., Ebr, J., Eckner, C., Egberts, K., Einecke, S., Ekoume, T. R. N., Elsässer, D., Ernenwein, J. -P., Espinoza, C., Evoli, C., Fairbairn, M., Falceta-Goncalves, D., Falcone, A., Farnier, C., Fasola, G., Fedorova, E., Fegan, S., Fernandez-Alonso, M., Fernández-Barral, A., Ferrand, G., Fesquet, M., Filipovic, M., Fioretti, V., Fontaine, G., Fornasa, M., Fortson, L., Freixas Coromina, L., Fruck, C., Fujita, Y., Fukazawa, Y., Funk, S., Füßling, M., Gabici, S., Gadola, A., Gallant, Y., Garcia, B., Garcia López, R., Garczarczyk, M., Gaskins, J., Gasparetto, T., Gaug, M., Gerard, L., Giavitto, G., Giglietto, N., Giommi, P., Giordano, F., Giro, E., Giroletti, M., Giuliani, A., Glicenstein, J. -F., Gnatyk, R., Godinovic, N., Goldoni, P., Gómez-Vargas, G., González, M. M., González, J. M., Götz, D., Graham, J., Grandi, P., Granot, J., Green, A. J., Greenshaw, T., Griffiths, S., Gunji, S., Hadasch, D., Hara, S., Hardcastle, M. J., Hassan, T., Hayashi, K., Hayashida, M., Heller, M., Helo, J. C., Hermann, G., Hinton, J., Hnatyk, B., Hofmann, W., Holder, J., Horan, D., Hörandel, J., Horns, D., Horvath, P., Hovatta, T., Hrabovsky, M., Hrupec, D., Humensky, T. B., Hütten, M., Iarlori, M., Inada, T., Inome, Y., Inoue, S., Inoue, T., Inoue, Y., Iocco, F., Ioka, K., Iori, M., Ishio, K., Iwamura, Y., Jamrozy, M., Janecek, P., Jankowsky, D., Jean, P., Jung-Richardt, I., Jurysek, J., Kaaret, P., Karkar, S., Katagiri, H., Katz, U., Kawanaka, N., Kazanas, D., Khélifi, B., Kieda, D. B., Kimeswenger, S., Kimura, S., Kisaka, S., Knapp, J., Knödlseder, J., Koch, B., Kohri, K., Komin, N., Kosack, K., Kraus, M., Krause, M., Krauß, F., Kubo, H., Kukec Mezek, G., Kuroda, H., Kushida, J., La Palombara, N., Lamanna, G., Lang, R. G., Lapington, J., Le Blanc, O., Leach, S., Lees, J. -P., Lefaucheur, J., Leigui de Oliveira, M. A., Lenain, J. -P., Lico, R., Limon, M., Lindfors, E., Lohse, T., Lombardi, S., Longo, F., López, M., López-Coto, R., Lu, C. -C., Lucarelli, F., Luque-Escamilla, P. L., Lyard, E., Maccarone, M. C., Maier, G., Majumdar, P., Malaguti, G., Mandat, D., Maneva, G., Manganaro, M., Mangano, S., Marcowith, A., Marín, J., Markoff, S., Martí, J., Martin, P., Martínez, M., Martínez, G., Masetti, N., Masuda, S., Maurin, G., Maxted, N., Mazin, D., Medina, C., Melandri, A., Mereghetti, S., Meyer, M., Minaya, I. A., Mirabal, N., Mirzoyan, R., Mitchell, A., Mizuno, T., Moderski, R., Mohammed, M., Mohrmann, L., Montaruli, T., Moralejo, A., Morcuende-Parrilla, D., Mori, K., Morlino, G., Morris, P., Morselli, A., Moulin, E., Mukherjee, R., Mundell, C., Murach, T., Muraishi, H., Murase, K., Nagai, A., Nagataki, S., Nagayoshi, T., Naito, T., Nakamori, T., Nakamura, Y., Niemiec, J., Nieto, D., Nikołajuk, M., Nishijima, K., Noda, K., Nosek, D., Novosyadlyj, B., Nozaki, S., O'Brien, P., Oakes, L., Ohira, Y., Ohishi, M., Ohm, S., Okazaki, N., Okumura, A., Ong, R. A., Orienti, M., Orito, R., Osborne, J. P., Ostrowski, M., Otte, N., Oya, I., Padovani, M., Paizis, A., Palatiello, M., Palatka, M., Paoletti, R., Paredes, J. M., Pareschi, G., Parsons, R. D., Pe'er, A., Pech, M., Pedaletti, G., Perri, M., Persic, M., Petrashyk, A., Petrucci, P., Petruk, O., Peyaud, B., Pfeifer, M., Piano, G., Pisarski, A., Pita, S., Pohl, M., Polo, M., Pozo, D., Prandini, E., Prast, J., Principe, G., Prokhorov, D., Prokoph, H., Prouza, M., Pühlhofer, G., Punch, M., Pürckhauer, S., Queiroz, F., Quirrenbach, A., Rainò, S., Razzaque, S., Reimer, O., Reimer, A., Reisenegger, A., Renaud, M., Rezaeian, A. H., Rhode, W., Ribeiro, D., Ribó, M., Richtler, T., Rico, J., Rieger, F., Riquelme, M., Rivoire, S., Rizi, V., Rodriguez, J., Rodriguez Fernandez, G., Rodríguez Vázquez, J. J., Rojas, G., Romano, P., Romeo, G., Rosado, J., Rovero, A. C., Rowell, G., Rudak, B., Rugliancich, A., Rulten, C., Sadeh, I., Safi-Harb, S., Saito, T., Sakaki, N., Sakurai, S., Salina, G., Sánchez-Conde, M., Sandaker, H., Sandoval, A., Sangiorgi, P., Sanguillon, M., Sano, H., Santander, M., Sarkar, S., Satalecka, K., Saturni, F. G., Schioppa, E. J., Schlenstedt, S., Schneider, M., Schoorlemmer, H., Schovanek, P., Schulz, A., Schussler, F., Schwanke, U., Sciacca, E., Scuderi, S., Seitenzahl, I., Semikoz, D., Sergijenko, O., Servillat, M., Shalchi, A., Shellard, R. C., Sidoli, L., Siejkowski, H., Sillanpää, A., Sironi, G., Sitarek, J., Sliusar, V., Slowikowska, A., Sol, H., Stamerra, A., Stanič, S., Starling, R., Stawarz, Ł., Stefanik, S., Stephan, M., Stolarczyk, T., Stratta, G., Straumann, U., Suomijarvi, T., Supanitsky, A. D., Tagliaferri, G., Tajima, H., Tavani, M., Tavecchio, F., Tavernet, J. -P., Tayabaly, K., Tejedor, L. A., Temnikov, P., Terada, Y., Terrier, R., Terzic, T., Teshima, M., Testa, V., Thoudam, S., Tian, W., Tibaldo, L., Tluczykont, M., Todero Peixoto, C. J., Tokanai, F., Tomastik, J., Tonev, D., Tornikoski, M., Torres, D. F., Torresi, E., Tosti, G., Tothill, N., Tovmassian, G., Travnicek, P., Trichard, C., Trifoglio, M., Troyano Pujadas, I., Tsujimoto, S., Umana, G., Vagelli, V., Vagnetti, F., Valentino, M., Vallania, P., Valore, L., van Eldik, C., Vandenbroucke, J., Varner, G. S., Vasileiadis, G., Vassiliev, V., Vázquez Acosta, M., Vecchi, M., Vega, A., Vercellone, S., Veres, P., Vergani, S., Verzi, V., Vettolani, G. P., Viana, A., Vigorito, C., Villanueva, J., Voelk, H., Vollhardt, A., Vorobiov, S., Vrastil, M., Vuillaume, T., Wagner, S. J., Wagner, R., Walter, R., Ward, J. E., Warren, D., Watson, J. J., Werner, F., White, M., White, R., Wierzcholska, A., Wilcox, P., Will, M., Williams, D. A., Wischnewski, R., Wood, M., Yamamoto, T., Yamazaki, R., Yanagita, S., Yang, L., Yoshida, T., Yoshiike, S., Yoshikoshi, T., Zacharias, M., Zaharijas, G., Zampieri, L., Zandanel, F., Zanin, R., Zavrtanik, M., Zavrtanik, D., Zdziarski, A. A., Zech, A., Zechlin, H., Zhdanov, V. I., Ziegler, A., Zorn, J.

2019

Language：English Publishing type：Research paper (scientific journal) Publisher：Science with the Cherenkov Telescope Array

The Cherenkov Telescope Array, CTA, will be the major global observatory for very high energy gamma-ray astronomy over the next decade and beyond. The scientific potential of CTA is extremely broad: from understanding the role of relativistic cosmic particles to the search for dark matter. CTA is an explorer of the extreme universe, probing environments from the immediate neighbourhood of black holes to cosmic voids on the largest scales. Covering a huge range in photon energy from 20 GeV to 300 TeV, CTA will improve on all aspects of performance with respect to current instruments. The observatory will operate arrays on sites in both hemispheres to provide full sky coverage and will hence maximize the potential for the rarest phenomena such as very nearby supernovae, gamma-ray bursts or gravitational wave transients. With 99 telescopes on the southern site and 19 telescopes on the northern site, flexible operation will be possible, with sub-arrays available for specific tasks. CTA will have important synergies with many of the new generation of major astronomical and astroparticle observatories. Multi-wavelength and multi-messenger approaches combining CTA data with those from other instruments will lead to a deeper understanding of the broad-band non-thermal properties of target sources. The CTA Observatory will be operated as an open, proposal-driven observatory, with all data available on a public archive after a pre-defined proprietary period. Scientists from institutions worldwide have combined together to form the CTA Consortium. This Consortium has prepared a proposal for a Core Programme of highly motivated observations. The programme, encompassing approximately 40% of the available observing time over the first ten years of CTA operation, is made up of individual Key Science Projects (KSPs), which are presented in this document....

DOI： 10.1142/10986

Evaluation of silicon photomultipliers for dual-mirror Small-Sized Telescopes of Cherenkov Telescope Array

Asano A, Berge D, Bonanno G, Bryan M, Gebhardt B, Grillo A, Hidaka N, Kachru P, Lapington J, Leach S, Nakamura Y, Okumura A, Romeo G, Ross D, Stephan M, Tajima H, Timpanaro M. C, White R, Yamane N, Zink A

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 912 page： 177 - 181 2018.12

Characterisation and testing of CHEC-M-A camera prototype for the small-sized telescopes of the Cherenkov telescope array

Zorn J., White R., Watson J. J., Armstrong T. P., Balzer A., Barcelo M., Berge D., Bose R., Brown A. M., Bryan M., Chadwick P. M., Clark P., Costantini H., Cotter G., Dangeon L., Daniel M., De Franco A., Deiml P., Fasola G., Funk S., Gebyehu M., Gironnet J., Graham J. A., Greenshaw T., Hinton J. A., Kraus M., Lapington J. S., Laporte P., Leach S. A., Le Blanc O., Malouf A., Molyneux P., Moore P., Prokoph H., Okumura A., Ross D., Rowell G., Sapozhnikov L., Schoorlemmer H., Sol H., Stephan M., Tajima H., Tibaldo L., Varner G., Zink A.

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 904 page： 44-63 2018.10

Final characterisation and design of the Gamma-ray Cherenkov Telescope (GCT) for the Cherenkov Telescope Array

Le Blanc O, Fasola G, Huet J. M, White R, Dmytriiev A, Sol H, Zech A, Abchiche A, Amans J. P, Armstrong T. P, Barcelo M, Berge D, Brown A. M, Buchholtz G, Chadwick P. M, Clark P, Cotter G, Dangeon L, De Frondat F, Deiml P, Dournaux J. L, Duffy C, Einecke S, Flis S, Funk S, Giavitto G, Gironnet J, Graham J. A, Greenshaw T, Hinton J. A, Jegouzo I, Kraus M, Lapington J. S, Laporte P, Leach S. A, Lloyd S, Minaya I. A, Morier R, Okumura A, Prokoph H, Ross D., R

GROUND-BASED AND AIRBORNE TELESCOPES VII Vol. 10700 2018

CTA Project 130: General Report

Teshima Masahiro, Kubo Hidetoshi, Totani Tomonori, Consortium for, the CTA-Japan

Meeting Abstracts of the Physical Society of Japan Vol. 73 ( 0 ) page： 412-412 - 412 2018

CTA Report 139: General Report

Kubo Hidetoshi, Inoue Tsuyoshi, Fukami Satoshi, Fukui Yasuo, Fujita Yutaka, Fujihara Chikako, He Haoning, Majumdar Pratik, Mazin Daniel, Masuda Shu, Matsumoto Hironori, Miura Chika, Inoue Yoshiyuki, Mizuno Tsunefumi, Muraishi Hiroshi, Murase Kohta, Mori Koji, Yanagita Shohei, Yamazaki Ryo, Yamamoto Tokonatsu, Yamamoto Hiroaki, Yoshiike Satoshi, Yoshikoshi Takanori, Inome Yusuke, Yoshida Atsumasa, Yoshida Tatsuo, Ri Ken, Lee Shiu-Hang (Herman), Iwamura Yuki, Warren Donald, Uchiyama Yasunobu, Ohishi Michiko, Ohoka Hideyuki, Ohira Yutaka, Okazaki Nao, Teshima Masahiro, Okumura Akira, Orito Reiko, Kagaya Mika, Kakuwa Jun, Kataoka Jun, Katagiri Hideaki, Katsukura Daisuke, Katsuda Satoru, Kato Sho, Kamimoto Takumi, Totani Tomonori, Kawanaka Norita, Kisaka Shota, Kimura Souichiro, Cui Xiaohong, Kushida Junko, Kumon Taku, Kuroda Hayato, Gunji Shuichi, Kohri Kazunori, Koyama Shu, Asano Akira, Kong Albert K. H., Saito Takayuki, Sakaki Naoto, Sakurai Shunsuke, Sasai Yoshinori, Sano Hidetoshi, Sawada Makoto, Shibata Toru, Dzhatdoev Timur, Suzuki Megumi, Asano Katsuaki, Sunada Yuji, Sekizaki Haruhito, Zenin Anatolii, Takata Jumpei, Takahashi Keitaro, Takahashi Tomoya, Takahashi Hiromitsu, Takahashi Mitsunari, Takahara Hiro, Tajima Hiroyasu, Ioka Kunihito, Tachihara Kengo, Tanaka Shuta, Tanaka Takaaki, Tanaka Manobu, Tanaka Yasuyuki, Taneda Yuuki, Tam Thomas P. H., Cheng K. S., Chikawa Michiyuki, Tsujimoto Shimpei, Ishio Kazuma, Tsuru Takeshi, Tian Wenwu, Terada Yukikatsu, Toma Kenji, Tokanai Fuyuki, Naito Tsuguya, Nakajima Daisuke, Nagataki Shigehiro, Nakamura Yuki, Nakamori Takeshi, Inada Tomohiro, Nakayama Kazunori, Nagayoshi Tsutomu, Nishijima Kyoshi, Nishiyama Gaku, Nozaki Seiya, Noda Koji, Barkov Maxim, Hadasch Daniela, Hayakawa Takahiro, Hayashi Katsuhiro, Inoue Susumu, Hayashida Masaaki, Hara Satoshi, Bamba Aya, Hidaka Naoya, Hirako Joe, Hiroshima Nagisa, Hirotani Kouichi, Hui David C. Y., Ferrand Gilles, Fukazawa Yasushi

Meeting Abstracts of the Physical Society of Japan Vol. 73 ( 0 ) page： 188 - 188 2018

CTA report 140: A Monte Carlo simulation study on gamma-ray like proton events in CTA and dependence on hadronic interaction models

Ohishi Michiko, Sasai Yoshinori, Takahashi Tomoya, Taneda Yuki, Chikawa Michiyuki, Nakamori Takeshi, Nishijima Kyoshi, Fujiwara Chikako, Miura Chika, Yoshikoshi Takanori, Yoshida Tatsuo, Okumura Akira, Ri Ken, Zenin Anatolii, the CTA-Japan Consortium, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki, Sakaki Naoto

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 189 - 189 2018

CTA report 135: Optimization of the trigger performance for the Small-Sized Telescope

Sasai Yoshinori, Sakaki Naoto, Takahashi Tomoya, Taneda Yuki, Chikawa Michiyuki, Nakamori Takeshi, Nishijina Kyoshi, Miura Chika, Yoshikoshi Takanori, Yoshida Tatsuo, Ri Ken, Ohishi Michiko, the CTA-Japan Consortium, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 418 - 418 2018

CTA report 132: A simulation study on CTA performance for the measurement of electron/positron spectrum in TeV region(III)

Ohishi Michiko, Sasai Yoshinori, Takahashi Tomoya, Taneda Yuki, Chikawa Michiyuki, Nakamori Takeshi, Nishijina Kyoshi, Miura Chika, Yoshikoshi Takanori, Yoshida Tatsuo, Ri Ken, Okumura Akira, the CTA-Japan Consortium, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki, Sakaki Naoto

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 487 - 487 2018

CTA Report 131: Monte Carlo performance studies of the Cherenkov Telescope Array under moonlight

Miura Chika, Sakaki Naoto, Sasai Yoshinori, Takahashi Tomoya, Taneda Yuki, Chikawa Michiyuki, Nakamori Takeshi, Nishijima Kyoshi, Yoshikoshi Takanori, Yoshida Tatsuo, Ri Ken, Ohishi Michiko, the CTA-Japan Consortium, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 413 - 413 2018

CTA report 143: Evaluation of the sensitivity of the Small-Sized Telescopes under moonlight

Sasai Yoshinori, Sakaki Naoto, Takahashi Tomoya, Tajima Hiroyasu, Taneda Yuki, Chikawa Michiyuki, Nakamura Yuki, Nakamori Takeshi, Nishijina Kyoshi, Fujihara Chikako, Miura Chika, Ohishi Michiko, Yoshikoshi Takanori, Yoshida Tatsuo, Ri Ken, Zenin Anatolii, the CTA-Japan Consortium, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 192 - 192 2018

CTA Report 141: Monte Carlo performance studies of the Cherenkov Telescope Array under moonlight (II)

Miura Chika, Sakaki Naoto, Sasai Yoshinori, Takahashi Tomoya, Taneda Yuki, Chikawa Michiyuki, Nakamori Takeshi, Nishijima Kyoshi, Fujihara Chikako, Yoshikoshi Takanori, Yoshida Tatsuo, Ohishi Michiko, Ri Ken, Zenin Anatolii, the CTA-Japan Consortium, Okumura Akira, Orito Reiko, Katagiri Hideaki, Kamimoto Takumi, Kushida Junko, Gunji Shuichi, Saito Takayuki

Meeting Abstracts of the Physical Society of Japan Vol. 73 page： 190 - 190 2018

The GCT camera for the Cherenkov Telescope Array

Lapington J. S., Abchiche A., Allan D., Amans J. -P., Armstrong T. P., Balzer A., Berge D., Boisson C., Bousquet J. -J., Bose R., Brown A. M., Bryan M., Buchholtz G., Buckley J., Chadwick P. M., Costantini H., Cotter G., Daniel M. K., De Franco A., De Frondat F., Dournaux J. -L., Dumas D., Ernenwein J. -P., Fasola G., Funk S., Gironnet J., Graham J. A., Greenshaw T., Hervet O., Hidaka N., Hinton J. A., Huet J. -M., Jankowsky D., Jegouzo I., Jogler T., Kawashima T., Kraus M., Laporte P., Leach S., Lefaucheur J., Markoff S., Melse T., Minaya I. A., Mohrmann L., Molyneux P., Moore P., Nolan S. J., Okumura A., Osborne J. P., Parsons R. D., Rosen S., Ross D., Rowell G., Rulten C. B., Sato Y., Sayede F., Schmoll J., Schoorlemmer H., Servillat M., Sol H., Stamatescu V., Stephan M., Stuik R., Sykes J., Tajima H., Thornhill J., Tibaldo L., Trichard C., Varner G., Vink J., Watson J. J., White R., Yamane N., Zech A., Zink A., Zorn J.

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 876 page： 1-4 2017.12

Prototyping hexagonal light concentrators using high-reflectance specular films for the Large-Sized Telescopes of the Cherenkov Telescope Array Reviewed

A. Okumura, et al.

Journal of Instrumentation Vol. 12 page： P12008 2017.12

Prototyping hexagonal light concentrators using high-reflectance specular films for the Large-Sized Telescopes of the Cherenkov Telescope Array

Okumura A., Dang T. V., Ono S., Tanaka S., Hayashida M., Hinton J., Katagiri H., Noda K., Teshima M., Yamamoto T., Yoshida T.

JOURNAL OF INSTRUMENTATION Vol. 12 2017.12

TARGET 5: A new multi-channel digitizer with triggering capabilities for gamma-ray atmospheric Cherenkov telescopes

Albert A., Funk S., Katagiri H., Kawashima T., Murphy M., Okumura A., Quagliani R., Sapozhnikov L., Shigenaka A., Tajima H., Tibaldo L., Vandenbroucke J., Varner G., Wu T.

ASTROPARTICLE PHYSICS Vol. 92 page： 49-61 2017.6

Prospects for Cherenkov Telescope Array Observations of the Young Supernova Remnant RX J1713.7-3946

Acero F., Aloisio R., Amans J., Amato E., Antonelli L. A., Aramo C., Armstrong T., Arqueros F., Asano K., Ashley M., Backes M., Balazs C., Balzer A., Bamba A., Barkov M., Barrio J. A., Benbow W., Bernloehr K., Beshley V., Bigongiari C., Biland A., Bilinsky A., Bissaldi E., Biteau J., Blanch O., Blasi P., Blazek J., Boisson C., Bonanno G., Bonardi A., Bonavolonta C., Bonnoli G., Braiding C., Brau-Nogue S., Bregeon J., Brown A. M., Bugaev V., Bulgarelli A., Bulik T., Burton M., Burtovoi A., Busetto G., Bottcher M., Cameron R., Capalbi M., Caproni A., Caraveo P., Carosi R., Cascone E., Cerruti M., Chaty S., Chen A., Chen X., Chernyakova M., Chikawa M., Chudoba J., Cohen-Tanugi J., Colafrancesco S., Conforti V., Contreras J. L., Costa A., Cotter G., Covino S., Covone G., Cumani P., Cusumano G., D'Ammando F., D'Urso D., Daniel M., Dazzi F., De Angelis A., De Cesare G., De Franco A., De Frondat F., Dal Pino E. M. de Gouveia, De Lisio C., Lopez R. de los Reyes, De Lotto B., de Naurois M., De Palma F., Del Santo M., Delgado C., della Volpe D., Di Girolamo T., Di Giulio C., Di Pierro F., Di Venere L., Doro M., Dournaux J., Dumas D., Dwarkadas V., Diaz C., Ebr J., Egberts K., Einecke S., Elsaesser D., Eschbach S., Falceta-Goncalves D., Fasola G., Fedorova E., Fernandez-Barral A., Ferrand G., Fesquet M., Fiandrini E., Fiasson A., Filipovic M. D., Fioretti V., Font L., Fontaine G., Franco F. J., Freixas Coromina L., Fujita Y., Fukui Y., Funk S., Forster A., Gadola A., Lopez R. Garcia, Garczarczyk M., Giglietto N., Giordano F., Giuliani A., Glicenstein J., Gnatyk R., Goldoni P., Grabarczyk T., Graciani R., Graham J., Grandi P., Granot J., Green A. J., Griffiths S., Gunji S., Hakobyan H., Hara S., Hassan T., Hayashida M., Heller M., Helo J. C., Hinton J., Hnatyk B., Huet J., Huetten M., Humensky T. B., Hussein M., Horandel J., Ikeno Y., Inada T., Inome Y., Inoue S., Inoue T., Inoue Y., Ioka K., Iori M., Jacquemier J., Janecek P., Jankowsky D., Jung I., Kaaret P., Katagiri H., Kimeswenger S., Kimura S., Knodlseder J., Koch B., Kocot J., Kohri K., Komin N., Konno Y., Kosack K., Koyama S., Kraus M., Kubo H., Mezek G. Kukec, Kushida J., La Palombara N., Lalik K., Lamanna G., Landt H., Lapington J., Laporte P., Lee S., Lees J., Lefaucheur J., Lenain J. -P., Leto G., Lindfors E., Lohse T., Lombardi S., Longo F., Lopez M., Lucarelli F., Luque-Escamilla P. L., Lopez-Coto R., Maccarone M. C., Maier G., Malaguti G., Mandat D., Maneva G., Mangano S., Marcowith A., Marti J., Martinez M., Martinez G., Masuda S., Maurin G., Maxted N., Melioli C., Mineo T., Mirabal N., Mizuno T., Moderski R., Mohammed M., Montaruli T., Moralejo A., Mori K., Morlino G., Morselli A., Moulin E., Mukherjee R., Mundell C., Muraishi H., Murase K., Nagataki S., Nagayoshi T., Naito T., Nakajima D., Nakamori T., Nemmen R., Niemiec J., Nieto D., Nievas-Rosillo M., Nikolajuk M., Nishijima K., Noda K., Nogues L., Nosek D., Novosyadlyj B., Nozaki S., Ohira Y., Ohishi M., Ohm S., Okumura A., Ong R. A., Orito R., Orlati A., Ostrowski M., Oya I., Padovani M., Palacio J., Palatka M., Paredes J. M., Pavy S., Pe'er A., Persic M., Petrucci P., Petruk O., Pisarski A., Pohl M., Porcelli A., Prandini E., Prast J., Principe G., Prouza M., Pueschel E., Puelhofer G., Quirrenbach A., Rameez M., Reimer O., Renaud M., Ribo M., Rico J., Rizi V., Rodriguez J., Fernandez G. Rodriguez, Rodriguez Vazquez J. J., Romano P., Romeo G., Rosado J., Rousselle J., Rowell G., Rudak B., Sadeh I., Safi-Harb S., Saito T., Sakaki N., Sanchez D., Sangiorgi P., Sano H., Santander M., Sarkar S., Sawada M., Schioppa E. J., Schoorlemmer H., Schovanek P., Schussler F., Sergijenko O., Servillat M., Shalchi A., Shellard R. C., Siejkowski H., Sillanpaa A., Simone D., Sliusar V., Sol H., Stanic S., Starling R., Stawarz L., Stefanik S., Stephan M., Stolarczyk T., Szanecki M., Szepieniec T., Tagliaferri G., Tajima H., Takahashi M., Takeda J., Tanaka M., Tanaka S., Tejedor L. A., Telezhinsky I., Temnikov P., Terada Y., Tescaro D., Teshima M., Testa V., Thoudam S., Tokanai F., Torres D. F., Torresi E., Tosti G., Townsley C., Travnicek P., Trichard C., Trifoglio M., Tsujimoto S., Vagelli V., Vallania P., Valore L., van Driel W., van Eldik C., Vandenbroucke J., Vassiliev V., Vecchi M., Vercellone S., Vergani S., Vigorito C., Vorobiov S., Vrastil M., Vazquez Acosta M. L., Wagner S. J., Wagner R., Wakely S. P., Walter R., Ward J. E., Watson J. J., Weinstein A., White M., White R., Wierzcholska A., Wilcox P., Williams D. A., Wischnewski R., Wojcik P., Yamamoto T., Yamamoto H., Yamazaki R., Yanagita S., Yang L., Yoshida T., Yoshida M., Yoshiike S., Yoshikoshi T., Zacharias M., Zampieri L., Zanin R., Zavrtanik M., Zavrtanik D., Zdziarski A., Zech A., Zechlin H., Zhdanov V., Ziegler A., Zorn J.

ASTROPHYSICAL JOURNAL Vol. 840 ( 2 ) 2017.5

Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild-Couder telescope prototype for the Cherenkov Telescope Array

Dournaux J. L., De Franco A., Laporte P., White R., Greenshaw T., Sol H., Abchiche A., Allan D., Amans J. P., Armstrong T. P., Balzer A., Berge D., Boisson C., Bousquet J. J., Brown A. M., Bryan M., Buchholtz G., Chadwick P. M., Costantini H., Cotter G., Daniel M., De Frondat F., Dumas D., Ernenwein J. P., Fasola G., Funk S., Gaudemard J., Graham J. A., Gironnet J., Hervet O., Hidaka N., Hinton J. A., Huet J. M., Jegouzo I., Jogler T., Kawashima T., Kraus M., Lapington J. S., Lefaucheur J., Markoff S., Melse T., Morhrmann L., Molnyeux P., Nolan S. J., Okumura A., Parsons R. D., Ross D., Rowell G., Sato Y., Sayede F., Schmoll J., Schoorlemmer H., Servillat M., Stamatescu V., Stephan M., Stuik R., Sykes J., Tajima H., Thornhill J., Tibaldo L., Trichard C., Vinkh J., Watson J., Yamane N., Zech A., Zink A.

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Vol. 845 page： 355-358 2017.2

TARGET 5: a new multi-channel digitizer with triggering capabilities for gamma-ray atmospheric Cherenkov telescopes Reviewed

A. Albert, S. Funk, T. Kawashima, M. Murphy, A. Okumura, R. Quagliani, L. Sapozhnikov, H. Tajima, L. Tibaldo, J. Vandenbroucke, G. Varner, T. Wu

Astroparticle Physics Vol. 92 page： 49-61 2017

Inauguration and First Light of the GCT-M Prototype for the Cherenkov Telescope Array

J. J. Watson, A. De Franco, A. Abchiche, D. Allan, J. -P. Amans, T. P. Armstrong, A. Balzer, D. Berge, C. Boisson, J. -J. Bousquet, A. M. Brown, M. Bryan, G. Buchholtz, P. M. Chadwick, H. Costantini, G. Cotter, M. K. Daniel, F. De Frondat, J. -L. Dournaux, D. Dumas, J. -P. Ernenwein, G. Fasola, S. Funk, J. Gironnet, J. A. Graham, T. Greenshaw, O. Hervet, N. Hidaka, J. A. Hinton, J. -M. Huet, I. Jegouzo, T. Jogler, M. Kraus, J. S. Lapington, P. Laporte, J. Lefaucheur, S. Markoff, T. Melse, L. Mohrmann, P. Molyneux, S. J. Nolan, A. Okumura, J. P. Osborne, R. D. Parsons, S. Rosen, D. Ross, G. Rowell, C. B. Rulten, Y. Sato, F. Sayede, J. Schmoll, H. Schoorlemmer, M. Servillat, H. Sol, V. Stamatescu, M. Stephan, R. Stuik, J. Sykes, H. Tajima, J. Thornhill, L. Tibaldo, C. Trichard, J. Vink, R. White, N. Yamane, A. Zech, A. Zink, J. Zorn

HIGH ENERGY GAMMA-RAY ASTRONOMY Vol. 1792 2017

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

The Gamma-ray Cherenkov Telescope (GCT) is a candidate for the Small Size Telescopes (SSTs) of the Cherenkov Telescope Array (CTA). Its purpose is to extend the sensitivity of CTA to gamma-ray energies reaching 300 TeV. Its dual-mirror optical design and curved focal plane enables the use of a compact camera of 0.4 m diameter, while achieving a field of view of above 8 degrees. Through the use of the digitising TARGET ASICs, the Cherenkov flash is sampled once per nanosecond continuously and then digitised when triggering conditions are met within the analogue outputs of the photosensors. Entire waveforms (typically covering 96 ns) for all 2048 pixels are then stored for analysis, allowing for a broad spectrum of investigations to be performed on the data. Two prototypes of the GCT camera are under development, with differing photosensors: Multi -Anode Photomultipliers (MAPMs) and Silicon Photomultipliers (SiPMs). During November 2015, the GCT MAPM (GCT-M) prototype camera was integrated onto the GCT structure at the Observatoire de Paris-Meudon, where it observed the first Cherenkov light detected by a prototype instrument for CTA.

DOI： 10.1063/1.4969027

The Gamma-ray Cherenkov Telescope for the Cherenkov Telescope Array

L. Tibaldo, A. Abchiche, D. Allan, J. -P. Amans, T. P. Armstrong, A. Balzer, D. Bergey, C. Boisson, J. -J. Bousquet, A. M. Brown, M. Bryan, G. Buchholtz, P. M. Chadwick, H. Costantini, G. Cotter, M. K. Daniels, A. De Franco, F. De Frondat, J. -L. Dournaux, D. Dumas, J. -P. Ernenwein, G. Fasola, S. Funk, J. Gironnet, J. A. Graham, T. Greenshaws, O. Hervet, N. Hidaka, J. A. Hintoni, J. -M. Huet, D. Jankowsky, I. Jegouzo, T. Jogler, M. Kraus, J. S. Lapington, P. Laporte, J. Lefaucheur, S. Markoff, T. Melse, L. Mohrmann, P. Molyneux, S. J. Nolan, A. Okumura, J. P. Osborne, R. D. Parsons, S. Rosen, D. Ross, G. Rowell, C. B. Rulten, Y. Sato, F. Sayede, J. Schmoll, H. Schoorlemmer, M. Servillat, H. Sol, V. Stamatescu, M. Stephan, R. Stuik, J. Sykes, H. Tajima, J. Thornhill, C. Trichard, J. Vink, J. J. Watson, R. White, N. Yamane, A. Zech, A. Zink, J. Zorn

HIGH ENERGY GAMMA-RAY ASTRONOMY Vol. 1792 2017

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

The Cherenkov Telescope Array (CTA) is a forthcoming ground-based observatory for very-high-energy gamma rays. CTA will consist of two arrays of imaging atmospheric Cherenkov telescopes in the Northern and Southern hemispheres, and will combine telescopes of different types to achieve unprecedented performance and energy coverage. The Gamma-ray Cherenkov Telescope (GCT) is one of the small-sized telescopes proposed for CTA to explore the energy range from a few TeV to hundreds of TeV with a field of view greater than or similar to 8 degrees and angular resolution of a few arcminutes. The GCT design features dual-mirror SchwarzschildCouder optics and a compact camera based on densely-pixelated photodetectors as well as custom electronics. In this contribution we provide an overview of the GCT project with focus on prototype development and testing that is currently ongoing. We present results obtained during the first on-telescope campaign in late 2015 at the Observatoire de Paris-Meudon, during which we recorded the first Cherenkov images from atmospheric showers with the GCT multi-anode photomultiplier camera prototype. We also discuss the development of a second GCT camera prototype with silicon photomultipliers as photosensors, and plans toward a contribution to the realisation of CTA.

DOI： 10.1063/1.4969025

TARGET: A Digitizing And Trigger ASIC For The Cherenkov Telescope Array

S. Funk, D. Jankowsky, H. Katagiri, M. Kraus, A. Okumura, H. Schoorlemmer, A. Shigenaka, H. Tajima, L. Tibaldo, G. Varner, A. Zink, J. Zorn

HIGH ENERGY GAMMA-RAY ASTRONOMY Vol. 1792 2017

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

The future ground-based gamma-ray observatory Cherenkov Telescope Array (CTA) will feature multiple types of imaging atmospheric Cherenkov telescopes, each with thousands of pixels. To be affordable, camera concepts for these telescopes have to feature low cost per channel and at the same time meet the requirements for CTA in order to achieve the desired scientific goals. We present the concept of the TeV Array Readout Electronics with GSa/s sampling and Event Trigger (TARGET) Application Specific Circuit (ASIC), envisaged to be used in the cameras of various CTA telescopes, e. g. the Gamma-ray Cherenkov Telescope (GCT), a proposed 2-Mirror Small-Sized Telescope, and the Schwarzschild-Couder Telescope (SCT), a proposed Medium-Sized Telescope. In the latest version of this readout concept the sampling and trigger parts are split into dedicated ASICs, TARGET C and T5TEA, both providing 16 parallel input channels. TARGET C features a tunable sampling rate (usually 1 GSa/s), a 16k sample deep buffer for each channel and on-demand digitization and transmission of waveforms with typical spans of similar to 100 ns. The trigger ASIC, T5TEA, provides 4 low voltage differential signal (LVDS) trigger outputs and can generate a pedestal voltage independently for each channel. Trigger signals are generated by T5TEA based on the analog sum of the input in four independent groups of four adjacent channels and compared to a threshold set by the user. Thus, T5TEA generates four LVDS trigger outputs, as well as 16 pedestal voltages fed to TARGET C independently for each channel. We show preliminary results of the characterization and testing of TARGET C and T5TEA.

DOI： 10.1063/1.4969033