Faculty Profiles - TAMURA Yoichi

Papers - TAMURA Yoichi

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Bound star clusters observed in a lensed galaxy 460 Myr after the Big Bang Reviewed International coauthorship International journal Open Access

Angela Adamo, Larry D. Bradley, Eros Vanzella, Adélaïde Claeyssens, Brian Welch, Jose M. Diego, Guillaume Mahler, Masamune Oguri, Keren Sharon, Abdurro’uf, Tiger Yu Yang Hsiao, Xinfeng Xu, Matteo Messa, Augusto E. Lassen, Erik Zackrisson, Gabriel Brammer, Dan Coe, Vasily Kokorev, Massimo Ricotti, Adi Zitrin, Seiji Fujimoto, Akio K. Inoue, Tom Resseguier, Jane R. Rigby, Yolanda Jiménez-Teja, Rogier A. Windhorst, Takuya Hashimoto, Yoichi Tamura

Nature Vol. 632 ( 8025 ) page： 513 - 516 2024.8

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PORTFOLIO

The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. 1). However, it is an intrinsically ultraviolet faint galaxy, in the range of those now thought to drive the reionization of the Universe2–4. Hitherto the smallest features resolved in a galaxy at a comparable redshift are between a few hundreds and a few tens of parsecs (pc)5,6. Here we report JWST observations of the Cosmic Gems. The light of the galaxy is resolved into five star clusters located in a region smaller than 70 pc. They exhibit minimal dust attenuation and low metallicity, ages younger than 50 Myr and intrinsic masses of about 106M⊙. Their lensing-corrected sizes are approximately 1 pc, resulting in stellar surface densities near 105M⊙ pc−2, three orders of magnitude higher than typical young star clusters in the local Universe7. Despite the uncertainties inherent to the lensing model, they are consistent with being gravitationally bound stellar systems, that is, proto-globular clusters. We conclude that star cluster formation and feedback likely contributed to shaping the properties of galaxies during the epoch of reionization.

DOI： 10.1038/s41586-024-07703-7

FINER: Far-Infrared Nebular Emission Receiver for the Large Millimeter Telescope International coauthorship International journal Open Access

Yoichi Tamura, Takeshi Sakai, Ryohei Kawabe, Takafumi Kojima, Akio Taniguchi, Tatsuya Takekoshi, Haoran Kang, Wenlei Shan, Masato Hagimoto, Norika Okauchi, Airi Tetsuka, Akio K. Inoue, Kotaro Kohno, Kunihiko Tanaka, Tom J.L.C. Bakx, Yoshinobu Fudamoto, Kazuyuki Fujita, Yuichi Harikane, Takuya Hashimoto, Bunyo Hatsukade, David H. Hughes, Takahiro Iino, Yuki Kimura, Hiroyuki Maezawa, Yuichi Matsuda, Ken Mawatari, Taku Nakajima, Shunichi Nakatsubo, Tai Oshima, Hideo Sagawa, F. Peter Schloerb, Shigeru Takahashi, Kotomi Taniguchi, Akiyoshi Tsujita, Hideki Umehata, Teppei Yonetsu, Min S. Yun

Proceedings of SPIE - The International Society for Optical Engineering Vol. 13102 2024

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPIE-INT SOC OPTICAL ENGINEERING

Unveiling the emergence and prevalence of massive/bright galaxies during the epoch of reionization and beyond, within the first 600 million years of the Universe, stands as a pivotal pursuit in astronomy. Remarkable progress has been made by JWST in identifying an immense population of bright galaxies, which hints at exceptionally efficient galaxy assembly processes. However, the underlying physical mechanisms propelling their rapid growth remain unclear. With this in mind, millimeter and submillimeter-wave spectroscopic observations of redshifted far-infrared spectral lines, particularly the [O iii] 88 µm and [C ii] 158 µm lines, offers a crucial pathway to address this fundamental query. To this end, we develop a dual-polarization sideband-separating superconductor-insulator-superconductor (SIS) mixer receiver, FINER, for the Large Millimeter Telescope (LMT) situated in Mexico. Harnessing advancements from ALMA's wideband sensitivity upgrade (WSU) technology, FINER covers radio frequencies spanning 120-360 GHz, delivering an instantaneous intermediate frequency (IF) of 3-21 GHz per sideband per polarization, which is followed by a set of 10.24 GHz-wide digital spectrometers. At 40% of ALMA's light-collecting area, the LMT's similar atmospheric transmittance and FINER's 5 times wider bandwidth compared to ALMA culminate in an unparalleled spectral scanning capability in the northern hemisphere, paving the way for finer spectral-resolution detection of distant galaxies.

DOI： 10.1117/12.3017788

Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The Core of the Highest-redshift Galaxy Overdensity at z = 7.88 Confirmed by NIRSpec/JWST Reviewed International coauthorship International journal Open Access

T. Hashimoto, J. Álvarez-Márquez, Y. Fudamoto, L. Colina, A. K. Inoue, Y. Nakazato, D. Ceverino, N. Yoshida, L. Costantin, Y. Sugahara, A. Crespo Gómez, C. Blanco-Prieto, K. Mawatari, S. Arribas, R. Marques-Chaves, M. Pereira-Santaella, T. J.L.C. Bakx, M. Hagimoto, T. Hashigaya, H. Matsuo, Y. Tamura, M. Usui, Y. W. Ren

The Astrophysical Journal Letters Vol. 955 ( 1 ) page： L2 2023.9

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

The protoclusters in the epoch of reionization, traced by galaxy overdensity regions, are ideal laboratories for studying the process of stellar assembly and cosmic reionization. We present the spectroscopic confirmation of the core of the most distant protocluster at z = 7.88, A2744-z7p9OD, with the James Webb Space Telescope NIRSpec integral field unit spectroscopy. The core region includes as many as four galaxies detected in [O iii] 4960 and 5008 Å in a small area of ∼3″ × 3″, corresponding to ∼11 × 11 kpc, after the lensing magnification correction. Three member galaxies are also tentatively detected in dust continuum in Atacama Large Millimeter/submillimeter Array Band 6, which is consistent with their red ultraviolet continuum slopes, β ∼ −1.3. The member galaxies have stellar masses in the range of log(M */M ⊙) ∼7.6-9.2 and star formation rates of ∼3-50 M ⊙ yr−1, showing a diversity in their properties. FirstLight cosmological simulations reproduce the physical properties of the member galaxies including the stellar mass, [O iii] luminosity, and dust-to-stellar mass ratio, and predict that the member galaxies are on the verge of merging in a few to several tens of Myr to become a large galaxy with M * ∼ 6 × 109 M ⊙. The presence of a multiple merger and evolved galaxies in the core region of A2744-z7p9OD indicates that environmental effects are already at work 650 Myr after the Big Bang.

DOI： 10.3847/2041-8213/acf57c

The 300 pc Resolution Imaging of a z = 8.31 Galaxy: Turbulent Ionized Gas and Potential Stellar Feedback 600 Million Years after the Big Bang Reviewed International coauthorship International journal Open Access

Yoichi Tamura, Tom J. L. C. Bakx, Akio K. Inoue, Takuya Hashimoto, Tsuyoshi Tokuoka, Chihiro Imamura, Bunyo Hatsukade, Minju M. Lee, Kana Moriwaki, Takashi Okamoto, Kazuaki Ota, Hideki Umehata, Naoki Yoshida, Erik Zackrisson, Masato Hagimoto, Hiroshi Matsuo, Ikkoh Shimizu, Yuma Sugahara, Tsutomu T. Takeuchi

The Astrophysical Journal Vol. 952 ( 1 ) page： 9 2023.7

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：IOP Publishing Ltd

We present the results of 300 pc resolution Atacama Large Millimeter/submillimeter Array imaging of the [O iii] 88 & mu;m line and dust continuum emission from a z = 8.312 Lyman-break galaxy MACS0416_Y1. The velocity-integrated [O iii] emission has three peaks that are likely associated with three young stellar clumps of MACS0416_Y1, while the channel map shows a complicated velocity structure with little indication of a global velocity gradient unlike what was found in [C ii] 158 & mu;m at a larger scale, suggesting random bulk motion of ionized gas clouds inside the galaxy. In contrast, dust emission appears as two individual clumps apparently separating or bridging the [O iii]/stellar clumps. The cross-correlation coefficient between dust and ultraviolet-related emission (i.e., [O iii] and ultraviolet continuum) is unity on a galactic scale, while it drops at <1 kpc, suggesting well-mixed geometry of multiphase interstellar media on subkiloparsec scales. If the cutoff scale characterizes different stages of star formation, the cutoff scale can be explained by gravitational instability of turbulent gas. We also report on a kiloparsec-scale off-center cavity embedded in the dust continuum image. This could be a superbubble producing galactic-scale outflows, since the energy injection from the 4 Myr starburst suggested by a spectral energy distribution analysis is large enough to push the surrounding media creating a kiloparsec-scale cavity.

DOI： 10.3847/1538-4357/acd637

The bright extragalactic ALMA redshift survey (BEARS) - II. Millimetre photometry of gravitational lens candidates International coauthorship Open Access

Bendo, GJ; Urquhart, SA; Serjeant, S; Bakx, T; Hagimoto, M; Cox, P; Neri, R; Lehnert, MD; Dannerbauer, H; Amvrosiadis, A; Andreani, P; Baker, AJ; Beelen, A; Berta, S; Borsato, E; Buat, ; Butler, KM; Cooray, A; De Zotti, G; Dunne, L; Dye, S; Eales, S; Enia, A; Fan, L; Gavazzi, R; González-Nuevo, J; Harris, A; Herrera, CN; Hughes, DH; Ismail, D; Jones, BM; Kohno, K; Krips, M; Lagache, G; Marchetti, L; Massardi, M; Messias, H; Negrello, M; Omont, A; Pérez-Fournon, ; Riechers, DA; Scott, D; Smith, MWL; Stanley, F; Tamura, Y; Temi, P; van der Werf, P; Verma, A; Vlahakis, C; Weiss, A; Yang, C; Young, AJ

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 522 ( 2 ) page： 2995 - 3017 2023.4

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

We present 101- and 151-GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500-μm flux densities >80 mJy and 250–500-μm colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500-μm sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500-μm Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ∼15 per cent, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ∼2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.

DOI： 10.1093/mnras/stac3771

Possible Systematic Rotation in the Mature Stellar Population of a z = 9.1 Galaxy

Tsuyoshi Tokuoka, Akio K. Inoue, Takuya Hashimoto, Richard S. Ellis, Nicolas Laporte, Yuma Sugahara, Hiroshi Matsuo, Yoichi Tamura, Yoshinobu Fudamoto, Kana Moriwaki, Guido Roberts-Borsani, Ikkoh Shimizu, Satoshi Yamanaka, Naoki Yoshida, Erik Zackrisson, Wei Zheng

The Astrophysical Journal Letters Vol. 944 ( 2 ) page： 19 2023.2

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

We present new observations with the Atacama Large Millimeter/submillimeter Array for a gravitationally lensed galaxy at z = 9.1, MACS1149-JD1. [O iii] 88 μm emission is detected at 10σ with a spatial resolution of 1/40.3 kpc in the source plane, enabling the most distant morphokinematic study of a galaxy. The [O iii] emission is distributed smoothly without any resolved clumps and shows a clear velocity gradient with "V obs/2σ tot = 0.84 ± 0.23, where "V obs is the observed maximum velocity difference and σ tot is the velocity dispersion measured in the spatially integrated line profile, suggesting a rotating system. Assuming a geometrically thin self-gravitating rotation disk model, we obtain Vrot/σV=0.67-0.26+0.73, where V rot and σ V are the rotation velocity and velocity dispersion, respectively, still consistent with rotation. The resulting disk mass of 0.65-0.40+1.37×109 M ⊙ is consistent with being associated with the stellar mass identified with a 300 Myr old stellar population independently indicated by a Balmer break in the spectral energy distribution. We conclude that the most of the dynamical mass is associated with the previously identified mature stellar population that formed at z ∼15.

DOI： 10.3847/2041-8213/acb935

Data science based efficient and automated spectroscopy for submillimeter single-dish telescopes

Taniguchi A., Tamura Y., Ikeda S., Takekoshi T., Kawabe R., Kohno K., Sakai T.

2023 35th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2023 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：2023 35th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2023

In this paper, we present a new data scientific approach for efficient and automated spectroscopy with millimeter and submillimeter single-dish telescopes. The proposed approach avoids direct subtraction between two noisy spectra (i.e. on-source and off-source spectra) that is common in the current data reduction: It then offers us to improve the observation sensitivity by a factor of 2 and reduce artificial baseline ripples in parallel with developing observational instruments. We demonstrate such upgrades in the real observed spectra taken by existing large millimeter single-dish telescopes. We finally discuss the application of the proposed approach for the future large submillimeter single-dish telescopes that will yield petabytes of data resulting from sensitive, wide field (1°2), and wide band (>100 GHz) imaging spectroscopy.

DOI： 10.23919/URSIGASS57860.2023.10265475

Wavefront sensor for millimeter/submillimeter-wave adaptive optics based on aperture-plane interferometry

Yoichi Tamura, Ryohei Kawabe, Yuhei Fukasaku, Kimihiro Kimura, Tetsutaro Ueda, Akio Taniguchi, Nozomi Okada, Hideo Ogawa, Ikumi Hashimoto, Tetsuhiro Minamidani, Noriyuki Kawaguchi, Nario Kuno, Yohei Togami, Masato Hagimoto, Satoya Nakano, Keiichi Matsuda, Sachiko K. Okumura, Tomoko Nakamura, Mikio Kurita, Tatsuya Takekoshi, Tai Oshima, Toshikazu Onishi, Kotaro Kohno

Proceedings of the SPIE Vol. 11445 page： 114451N 2020

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPIE

We present a concept of a millimeter wavefront sensor that allows real-time sensing of the surface of a groundbased millimeter/submillimeter telescope. It is becoming important for ground-based millimeter/submillimeter astronomy to make telescopes larger with keeping their surface accurate. To establish 'millimetric adaptive optics (MAO)' that instantaneously corrects the wavefront degradation induced by deformation of telescope optics, our wavefront sensor based on radio interferometry measures changes in excess path lengths from characteristic positions on the primary mirror surface to the focal plane. This plays a fundamental role in planed 50-m class submillimeter telescopes such as LST and AtLAST.

DOI： 10.1117/12.2561885

ALMA twenty-six arcmin<sup>2</sup>survey of GOODS-S at one millimeter (ASAGAO) Open Access

Hatsukade B., Kohno K., Yamaguchi Y., Umehata H., Ao Y., Aretxaga I., Caputi K.I., Dunlop J.S., Egami E., Espada D., Fujimoto S., Hayatsu N., Hughes D.H., Ikarashi S., Iono D., Ivison R.J., Kawabe R., Kodama T., Lee M., Matsuda Y., Nakanishi K., Ohta K., Ouchi M., Rujopakarn W., Suzuki T., Tamura Y., Ueda Y., Wang T., Wang W.H., Wilson G.W., Yoshimura Y., Yun M.S.

Proceedings of the International Astronomical Union page： 239 - 240 2020

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of the International Astronomical Union

The ALMA twenty-six arcmin2 survey of GOODS-S at one millimeter (ASAGAO) is a deep (1σ ∼61μJy/beam) and wide area (26 arcmin2) survey on a contiguous field at 1.2 mm. By combining with archival data, we obtained a deeper map in the same region (1σ ∼30μJy/beam-1, synthesized beam size 0.59″ × 0.53″), providing the largest sample of sources (25 sources at 5σ, 45 sources at 4.5σ) among ALMA blank-field surveys. The median redshift of the 4.5σ sources is 2.4. The number counts shows that 52% of the extragalactic background light at 1.2 mm is resolved into discrete sources. We create IR luminosity functions (LFs) at z = 1-3, and constrain the faintest luminosity of the LF at 2 < z < 3. The LFs are consistent with previous results based on other ALMA and SCUBA-2 observations, which suggests a positive luminosity evolution and negative density evolution.

DOI： 10.1017/S1743921319009542

First light demonstration of the integrated superconducting spectrometer Reviewed

Akira Endo, Kenichi Karatsu, Yoichi Tamura, Tai Oshima, Akio Taniguchi, Tatsuya Takekoshi, Shin’ichiro Asayama, Tom J. L. C. Bakx, Sjoerd Bosma, Juan Bueno, Kah Wuy Chin, Yasunori Fujii, Kazuyuki Fujita, Robert Huiting, Soh Ikarashi, Tsuyoshi Ishida, Shun Ishii, Ryohei Kawabe, Teun M. Klapwijk, Kotaro Kohno, Akira Kouchi, Nuria Llombart, Jun Maekawa, Vignesh Murugesan, Shunichi Nakatsubo, Masato Naruse, Kazushige Ohtawara, Alejandro Pascual Laguna, Junya Suzuki, Koyo Suzuki, David J. Thoen, Takashi Tsukagoshi, Tetsutaro Ueda, Pieter J. de Visser, Paul P. van der Werf, Stephen J. C. Yates, Yuki Yoshimura, Ozan Yurduseven, Jochem J. A. Baselmans

Nature Astronomy Vol. 3 ( 11 ) page： 989 - 996 2019.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media {LLC}

Ultra-wideband 3D imaging spectrometry in the millimeter-submillimeter
(mm-submm) band is an essential tool for uncovering the dust-enshrouded portion
of the cosmic history of star formation and galaxy evolution. However, it is
challenging to scale up conventional coherent heterodyne receivers or
free-space diffraction techniques to sufficient bandwidths ($\geq$1 octave) and
numbers of spatial pixels (>$10^2$). Here we present the design and first
astronomical spectra of an intrinsically scalable, integrated superconducting
spectrometer, which covers 332-377 GHz with a spectral resolution of $F/\Delta
F \sim 380$. It combines the multiplexing advantage of microwave kinetic
inductance detectors (MKIDs) with planar superconducting filters for dispersing
the signal in a single, small superconducting integrated circuit. We
demonstrate the two key applications for an instrument of this type: as an
efficient redshift machine, and as a fast multi-line spectral mapper of
extended areas. The line detection sensitivity is in excellent agreement with
the instrument design and laboratory performance, reaching the atmospheric
foreground photon noise limit on sky. The design can be scaled to bandwidths in
excess of an octave, spectral resolution up to a few thousand and frequencies
up to $\sim$1.1 THz. The miniature chip footprint of a few $\mathrm{cm^2}$
allows for compact multi-pixel spectral imagers, which would enable
spectroscopic direct imaging and large volume spectroscopic surveys that are
several orders of magnitude faster than what is currently possible.

DOI： 10.1038/s41550-019-0850-8

Gas filaments of the cosmic web located around active galaxies in a protocluster Reviewed

Umehata, H., Fumagalli, M., Smail, I., Matsuda, Y., Swinbank, A. M., Cantalupo, S., Sykes, C., Ivison, R. J., Steidel, C. C., Shapley, A. E., Vernet, J., Yamada, T., Tamura, Y., Kubo, M., Nakanishi, K., Kajisawa, M., Hatsukade, B., Kohno, K.

Science Vol. 366 ( 6461 ) page： 97 - + 2019.10

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

Cosmological simulations predict that the Universe contains a network of intergalactic gas filaments, within which galaxies form and evolve. However, the faintness of any emission from these filaments has limited tests of this prediction. We report the detection of rest-frame ultraviolet Lyman-α radiation from multiple filaments extending more than one megaparsec between galaxies within the SSA22 protocluster at a redshift of 3.1. Intense star formation and supermassive black-hole activity is occurring within the galaxies embedded in these structures, which are the likely sources of the elevated ionizing radiation powering the observed Lyman-α emission. Our observations map the gas in filamentary structures of the type thought to fuel the growth of galaxies and black holes in massive protoclusters....

DOI： 10.1126/science.aaw5949

Big Three Dragons: A z = 7.15 Lyman-break galaxy detected in [O III] 88 μm, [CII] 158 μm, and dust continuum with ALMA Reviewed

Takuya Hashimoto, Akio K Inoue, Ken Mawatari, Yoichi Tamura, Hiroshi Matsuo, Hisanori Furusawa, Yuichi Harikane, Takatoshi Shibuya, Kirsten K Knudsen, Kotaro Kohno, Yoshiaki Ono, Erik Zackrisson, Takashi Okamoto, Nobunari Kashikawa, Pascal A Oesch, Masami Ouchi, Kazuaki Ota, Ikkoh Shimizu, Yoshiaki Taniguchi, Hideki Umehata, Darach Watson

Publications of the Astronomical Society of Japan Vol. 71 ( 4 ) 2019.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oxford University Press (OUP)

<title>Abstract</title>
We present new ALMA observations and physical properties of a Lyman break galaxy at z = 7.15. Our target, B14-65666, has a bright ultra-violet (UV) absolute magnitude, MUV ≈ −22.4, and has been spectroscopically identified in Lyα with a small rest-frame equivalent width of ≈4 Å. A previous Hubble Space TElescope (HST) image has shown that the target is composed of two spatially separated clumps in the rest-frame UV. With ALMA, we have newly detected spatially resolved [O iii] 88 μm, [C ii] 158 μm, and their underlying dust continuum emission. In the whole system of B14-65666, the [O iii] and [C ii] lines have consistent redshifts of 7.1520 ± 0.0003, and the [O iii] luminosity, (34.4 ± 4.1) × 108 L⊙, is about three times higher than the [C ii] luminosity, (11.0 ± 1.4) × 108 L⊙. With our two continuum flux densities, the dust temperature is constrained to be Td ≈ 50–60 K under the assumption of a dust emissivity index of βd = 2.0–1.5, leading to a large total infrared luminosity of LTIR ≈ 1 × 1012 L⊙. Owing to our high spatial resolution data, we show that the [O iii] and [C ii] emission can be spatially decomposed into two clumps associated with the two rest-frame UV clumps whose spectra are kinematically separated by ≈200 km s−1. We also find these two clumps have comparable UV, infrared, [O iii], and [C ii] luminosities. Based on these results, we argue that B14-65666 is a starburst galaxy induced by a major merger. The merger interpretation is also supported by the large specific star formation rate (defined as the star formation rate per unit stellar mass), sSFR $= 260^{+119}_{-57}\:$Gyr−1, inferred from our SED fitting. Probably, a strong UV radiation field caused by intense star formation contributes to its high dust temperature and the [O iii]-to-[C ii] luminosity ratio.

DOI： 10.1093/pasj/psz049

The onset of star formation 250 million years after the Big Bang Reviewed

Hashimoto, Takuya, Laporte, Nicolas, Mawatari, Ken, Ellis, Richard S., Inoue, Akio K., Zackrisson, Erik, Roberts-Borsani, Guido, Zheng, Wei, Tamura, Yoichi, Bauer, Franz E., Fletcher, Thomas, Harikane, Yuichi, Hatsukade, Bunyo, Hayatsu, Natsuki H., Matsuda, Yuichi, Matsuo, Hiroshi, Okamoto, Takashi, Ouchi, Masami, Pelló, Roser, Rydberg, Claes-Erik, Shimizu, Ikkoh, Taniguchi, Yoshiaki, Umehata, Hideki, Yoshida, Naoki

Nature Vol. 557 ( 7705 ) page： 392 - + 2018.5

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

A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang<SUP>1-3</SUP>. The abundance of star-forming galaxies is known to decline<SUP>4,5</SUP> from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we report spectroscopic observations of MACS1149-JD1<SUP>6</SUP>, a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age. We detect an emission line of doubly ionized oxygen at a redshift of 9.1096 ± 0.0006, with an uncertainty of one standard deviation. This precisely determined redshift indicates that the red rest-frame optical colour arises from a dominant stellar component that formed about 250 million years after the Big Bang, corresponding to a redshift of about 15. Our results indicate that it may be possible to detect such early episodes of star formation in similar galaxies with future telescopes....

DOI： 10.1038/s41586-018-0117-z

ADF22-WEB: A giant barred spiral starburst galaxy in the z=3.1 SSA22 protocluster core Open Access

Hideki Umehata, Charles C. Steidel, Ian Smail, Mark Swinbank, Erik B. Monson, David Rosario, Bret D. Lehmer, Kouichiro Nakanishi, Mariko Kubo, Daisuke Iono, David M. Alexander, Kotaro Kohno, Yoichi Tamura, Rob J. Ivison, Toshiki Saito, Ikki Mitsuhashi, Suo Huang, Yuichi Matsuda

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 2025.3

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

In the present-day universe, the most massive galaxies are ellipticals located in the cores of galaxy clusters, harboring the heaviest super-massive black holes (SMBHs). However, the mechanisms that drive the early growth phase and subsequent transformation of the morphology and kinematics of galaxies remain elusive. Here we report (sub)kiloparsec-scale observations of stars, gas, and dust in ADF22.A1, a bright dusty starburst galaxy at z=3.1, hosting a heavily obscured active galactic nucleus and residing in a proto-cluster core. ADF22.A1 is a giant spiral galaxy with the kinematics of a rotating disk with rotation velocity V-rot=530 +/- 10 km s(-1) and diameter >30 kpc. The high specific stellar angular momentum of this system, j(& lowast;)=3400 +/- 600 kpc km s(-1), requires a mechanism to effectively spin-up ADF22.A1, indicating the importance of accretion from the cosmic web to supply both gas and angular momentum to galaxies in their early gas-rich starburst phase. In its inner region, gas flows along dust lanes in a bar connected with the bright dusty core and the estimated mass ratio of the bulge to the SMBH matches the local relation, suggesting that bars are a key mechanism to shape the early co-evolution of these components. Comparison with cosmological simulations shows that ADF22.A1 will likely evolve into a massive elliptical, experiencing a significant reduction in angular momentum associated with subsequent galaxy mergers.

DOI： 10.1093/pasj/psaf010

RIOJA. Complex Dusty Starbursts in a Major Merger B14-65666 at <i>z</i>=7.15 Open Access

Yuma Sugahara, Javier alvarez-Marquez, Takuya Hashimoto, Luis Colina, Akio K. Inoue, Luca Costantin, Yoshinobu Fudamoto, Ken Mawatari, Yi W. Ren, Santiago Arribas, Tom J. L. C. Bakx, Carmen Blanco-Prieto, Daniel Ceverino, Alejandro Crespo Gomez, Masato Hagimoto, Takeshi Hashigaya, Rui Marques-Chaves, Hiroshi Matsuo, Yurina Nakazato, Miguel Pereira-Santaella, Yoichi Tamura, Mitsutaka Usui, Naoki Yoshida

ASTROPHYSICAL JOURNAL Vol. 981 ( 2 ) 2025.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP Publishing Ltd

We present JWST NIRCam imaging of B14-65666 ("Big Three Dragons"), a bright Lyman-break galaxy system (MUV = -22.5 mag) at z = 7.15. The high angular resolution of NIRCam reveals the complex morphology of two galaxy components: galaxy E has a compact core (E-core), surrounded by diffuse, extended, rest-frame optical emission, which is likely to be tidal tails; and galaxy W has a clumpy and elongated morphology with a blue UV slope (beta UV = -2.2 +/- 0.1). The flux excess, F356W - F444W, peaks at the E-core ( 1.05-0.09+0.08 mag), tracing the presence of strong [O iii] lambda lambda 4960,5008 emission. Atacama Large Millimeter/submillimeter Array archival data show that the bluer galaxy W is brighter in dust continua than the redder galaxy E, while the tails are bright in [O iii] 88 mu m. The UV/optical and submillimeter spectral energy distribution (SED) fitting confirms that B14-65666 is a major merger in a starburst phase as derived from the stellar mass ratio (3:1 to 2:1) and the star formation rate, similar or equal to 1 dex higher than the star formation main sequence at the same redshift. Galaxy E is a dusty (AV = 1.2 +/- 0.1 mag) starburst with a possible high dust temperature (>= 63-68 K). Galaxy W would have a low dust temperature (<= 27-33 K) or patchy stellar-and-dust geometry, as suggested by the IR excess and beta UV diagram. The high optical-to-far-IR [O iii] line ratio of the E-core shows its lower gas-phase metallicity (similar or equal to 0.2-0.4 Z circle dot) than galaxy W. These results agree with a scenario where major mergers disturb morphology and induce nuclear dusty starbursts triggered by less-enriched inflows. B14-65666 shows a picture of complex stellar buildup processes during major mergers in the epoch of reionization.

DOI： 10.3847/1538-4357/adb02a

Large Molecular and Dust Reservoir of a Gravitationally Lensed Submillimeter Galaxy behind the Lupus I Molecular Cloud Open Access

Yoichi Tamura, Akio Taniguchi, Tom J. L. C. Bakx, Itziar De Gregorio-Monsalvo, Masato Hagimoto, Soh Ikarashi, Ryohei Kawabe, Kotaro Kohno, Kouichiro Nakanishi, Tatsuya Takekoshi, Yoshito Shimajiri, Takashi Tsukagoshi, Bunyo Hatsukade, Daisuke Iono, Hideo Matsuhara, Kazuya Saigo, Masao Saito

The Astrophysical Journal Vol. 981 ( 1 ) 2025.3

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP Publishing Ltd

We report the Australian Telescope Compact Array and Nobeyama 45 m telescope detection of a remarkably bright (S1.1mm = 44 mJy) submillimeter galaxy MM J154506.4-344318 in emission lines at 48.5 and 97.0 GHz, respectively. We also identify part of an emission line at approximate to 218.3 GHz using the Atacama Large Millimeter/submillimeter Array (ALMA). Together with photometric redshift estimates and the ratio between the line and infrared luminosities, we conclude that the emission lines are most likely to be the J = 2-1, 4-3, and 9-8 transitions of 12CO at redshift z = 3.753 +/- 0.001. ALMA 1.3 mm continuum imaging reveals an arc and a spot separated by an angular distance of 1.'' 6 , indicative of a strongly lensed dusty star-forming galaxy with respective molecular and dust masses of logMmol/M circle dot approximate to 11.5 and logMdust/M circle dot approximate to 9.4 after being corrected for approximate to 6.6x gravitational magnification. The inferred dust-to-gas mass ratio is found to be high (approximate to 0.0083) among coeval dusty star-forming galaxies, implying the presence of a massive, chemically enriched reservoir of cool interstellar medium at z approximate to 4, or 1.6 Gyr after the Big Bang.

DOI： 10.3847/1538-4357/adb1b9

JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at <i>z</i> ∼ 7-14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe Open Access

Yuichi Harikane, Akio K. Inoue, Richard S. Ellis, Masami Ouchi, Yurina Nakazato, Naoki Yoshida, Yoshiaki Ono, Fengwu Sun, Riku A. Sato, Giovanni Ferrami, Seiji Fujimoto, Nobunari Kashikawa, Derek J. Mcleod, Pablo G. Perez-Gonzalez, Marcin Sawicki, Yuma Sugahara, Yi Xu, Satoshi Yamanaka, Adam C. Carnall, Fergus Cullen, James S. Dunlop, Eiichi Egami, Norman Grogin, Yuki Isobe, Anton M. Koekemoer, Nicolas Laporte, Chien-Hsiu Lee, Dan Magee, Hiroshi Matsuo, Yoshiki Matsuoka, Ken Mawatari, Kimihiko Nakajima, Minami Nakane, Yoichi Tamura, Hiroya Umeda, Hiroto Yanagisawa

ASTROPHYSICAL JOURNAL Vol. 980 ( 1 ) 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP Publishing Ltd

We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z similar to 7-14. Our sample is composed of 60 galaxies at z(spec )similar to 7-14, including recently confirmed galaxies at z(spec )= 12.34-14.18 with JWST, as well as new confirmations at z(spec) = 6.583-7.643 with -24 < M-UV < -21 mag using ALMA and Keck. Our JWST/NIRSpec observations have also revealed that very bright galaxy candidates at z similar to 10-13 identified from ground-based telescope images before JWST are passive galaxies at z similar to 3-4, emphasizing the necessity of strict screening and spectroscopy in the selection of the brightest galaxies at z > 10. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys, including PRIMER and COSMOS-Web. We find that similar to 70% of the bright galaxies at z similar to 7 exhibit clumpy morphologies with multiple subcomponents, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z greater than or similar to 10, bright galaxies are classified into two types of galaxies: extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including N iv]lambda 1486, indicating that at least two different processes (e.g., merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z greater than or similar to 10 and are responsible for their overabundance.

DOI： 10.3847/1538-4357/ad9b2c

Detection of the [O i] 63 μm emission line from the z=6.04 quasar J2054-0005 Open Access

Nozomi Ishii, Takuya Hashimoto, Carl Ferkinhoff, Matus Rybak, Akio K. Inoue, Tomonari Michiyama, Darko Donevski, Seiji Fujimoto, Dragan Salak, Nario Kuno, Hiroshi Matsuo, Ken Mawatari, Yoichi Tamura, Takuma Izumi, Tohru Nagao, Yurina Nakazato, Wataru Osone, Yuma Sugahara, Mitsutaka Usui, Koki Wakasugi, Hidenobu Yajima, Tom J. L. C. Bakx, Yoshinobu Fudamoto, Romain A. Meyer, Fabian Walter, Naoki Yoshida

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN Vol. 77 ( 1 ) page： 139 - 148 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

We report the highest-redshift detection of [O i] 63 mu m from a luminous quasar, J2054-0005, at z=6.04 based on the Atacama Large Millimeter/sub-millimeter Array (ALMA) Band 9 observations. The [O i] 63 mu m line luminosity is (4.5 +/- 1.5)x10(9)L(circle dot), corresponding to the [O i] 63 mu m-to-far-infrared luminosity ratio of approximate to 6.7 x10(-4), which is consistent with the value obtained in the local Universe. Remarkably, [O i] 63 mu m is as bright as [C ii] 158 mu m, resulting in the [O i]-to-[C ii] line luminosity ratio of 1.3 +/- 0.5. Based on a careful comparison of the luminosity ratios of [O i] 63 mu m, [C ii] 158 mu m, and dust continuum emission to models of photodissociation regions, we find that J2054-0005 has a gas density log(n(H)/cm(-3))=3.7 +/- 0.3 and an incident far-ultraviolet radiation field of log(G/G(0))=3.0 +/- 0.1, showing that [O i] 63 mu m serves as an important coolant of the dense and warm gas in J2054-0005. A close examination of the [O i] and [C ii] line profiles suggests that the [O i] line may be partially self-absorbed; however, deeper observations are needed to verify this conclusion. Regardless, the gas density and incident radiation field are in broad agreement with the values obtained in nearby star-forming galaxies and objects with [O i] 63 mu m observations at z=1-3 with the Herschel Space Observatory. These results demonstrate the power of ALMA high-frequency observations targeting [O i] 63 mu m to examine the properties of photodissociation regions in high-redshift galaxies.

DOI： 10.1093/pasj/psae105

A novel high-z submm galaxy efficient line survey in ALMA Bands 3 through 8 – an ANGELS pilot Open Access

T. J.L.C. Bakx, A. Amvrosiadis, G. J. Bendo, H. S.B. Algera, S. Serjeant, L. Bonavera, E. Borsato, X. Chen, P. Cox, J. González-Nuevo, M. Hagimoto, K. C. Harrington, R. J. Ivison, P. Kamieneski, L. Marchetti, D. A. Riechers, T. Tsukui, P. P. van der Werf, C. Yang, J. A. Zavala, P. Andreani, S. Berta, A. R. Cooray, G. De Zotti, S. Eales, R. Ikeda, K. K. Knudsen, I. Mitsuhashi, M. Negrello, R. Neri, A. Omont, D. Scott, Y. Tamura, P. Temi, S. A. Urquhart

Monthly Notices of the Royal Astronomical Society Vol. 535 ( 2 ) page： 1533 - 1574 2024.11

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

We use the Atacama Large sub/Millimetre Array (ALMA) to efficiently observe spectral lines across Bands 3, 4, 5, 6, 7, and 8 at high-resolution (0.5–0.1 arcsec) for 16 bright southern Herschel sources at 1.5 < z < 4.2. With only six and a half hours of observations, we reveal 66 spectral lines in 17 galaxies. These observations detect emission from CO (3−2) to CO(18−17), as well as atomic ([C I](1−0), (2−1), [O I] 145 μm and [N II] 205 μm) lines. Additional molecular lines are seen in emission (H2O and H2O+) and absorption (OH+ and CH+). The morphologies based on dust continuum ranges from extended sources to strong lensed galaxies with magnifications between 2 and 30. CO line transitions indicate a diverse set of excitation conditions with a fraction of the sources (∼ 35 per cent) showcasing dense, warm gas. The resolved gas to star formation surface densities vary strongly per source, and suggest that the observed diversity of dusty star-forming galaxies could be a combination of lensed, compact dusty starbursts and extended, potentially merging galaxies. The predicted gas depletion time-scales are consistent with 100 Myr to 1 Gyr, but require efficient fuelling from the extended gas reservoirs onto the more central starbursts, in line with the Doppler-shifted absorption lines that indicate inflowing gas for two out of six sources. This pilot paper explores a successful new method of observing spectral lines in large samples of galaxies, supports future studies of larger samples, and finds that the efficiency of this new observational method will be further improved with the planned ALMA Wideband Sensitivity Upgrade.

DOI： 10.1093/mnras/stae2409

JWST/NIRSpec spectroscopy of intermediate-mass quiescent galaxies at z ~ 3-4 Open Access

Riku A Sato, Akio K Inoue, Yuichi Harikane, Rhythm Shimakawa, Yuma Sugahara, Yoichi Tamura, Takuya Hashimoto, Kei Ito, Satoshi Yamanaka, Ken Mawatari, Yoshinobu Fudamoto, Yi W Ren

Monthly Notices of the Royal Astronomical Society Vol. 534 ( 4 ) page： 3552 - 3564 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

We present the analysis of three intermediate-mass quiescent galaxies (QGs) with stellar masses of similar to 10(10) M-circle dot at redshifts z similar to 3-4 using NIRSpec low-resolution spectroscopy. Utilizing the spectral energy distribution fitting code bagpipes, we confirm these target galaxies are consistent with quiescent population, with their specific star formation rates falling below 2 dex the star-forming main sequence at the same redshifts. Additionally, we identify these QGs to be less massive than those discovered in previous works, particularly prior to the JWST era. Two of our target galaxies exhibit the potentially blended H alpha + [N II] emission line within their spectra with signal-to-noise ratio >5. We discuss whether this feature comes from an active galactic nucleus (AGN) or star formation, although future high-resolution spectroscopy is required to reach a conclusion. One of the target galaxies is covered by JWST/NIRCam imaging of the Public Release IMaging for Extragalactic Research survey. Using the 2D profile fitting code galfit, we examine its morphology, revealing a disc-like profile with a Sersic index of n=1.1 +/- 0.1. On the size-mass relation, we find a potential distinction between less massive (log(10) (M-*/M-circle dot) < 10.3) and massive (log(10) (M-*/M-circle dot) > 10.3) QGs in their evolutionary pathways. The derived quenching time-scales for our targets are less than 1Gyr. This may result from these galaxies being quenched by AGN feedback, supporting the AGN scenario of the emission line features.

DOI： 10.1093/mnras/stae2300

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