研究者詳細 - 田村　陽一

論文 - 田村　陽一

分割表示 143 件中 81 - 100 件目／全件表示 >>

ALMA detection of the [OIII] 88 μm line in a highly-magnified Lyman break galaxy at z = 6.1 国際誌

Sunaga K., Tamura Y., Lee M., Mawatari K., Inoue A.K., Hashimoto T., Matsuo H., Taniguchi A.

Proceedings of the International Astronomical Union 15 巻 ( S341 ) 頁： 309 - 311 2020年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of the International Astronomical Union

We present a 4.7σ detection of the [OIII] 88 μm line in a gravitationally-lensed Lyman break galaxy, RXC J2248-ID3, using the Atacama Large Millimeter/submillimeter Array (ALMA). We did not detect [CII] 158 μm and rest-frame 90 μm dust continuum emission, suggesting that the bulk of the interstellar medium (ISM) is ionized. Our two-component SED model combining the previous Hubble Space Telescope (HST) data and new photometry obtained from Very Large Telescope (VLT), Spitzer and ALMA suggests the presence of young (∼2 Myr) and mature (∼600 Myr) stellar components with the metallicity of Z = 0.2Z . Our findings are in contrast with previous results claiming a very young, metal-poor stellar component.

DOI： 10.1017/s174392131900245x

Rapid evolution and transformation into quiescence?: ALMA view on z > 6 low-luminosity quasars 国際誌 Open Access

Izumi T., Onoue M., Matsuoka Y., Nagao T., Strauss M.A., Imanishi M., Kashikawa N., Fujimoto S., Kohno K., Toba Y., Umehata H., Goto T., Ueda Y., Shirakata H., Silverman J.D., Greene J.E., Harikane Y., Hashimoto Y., Ikarashi S., Iono D., Iwasawa K., Lee C.H., Minezaki T., Nakanishi K., Tamura Y., Tang J.J., Taniguchi A.

Proceedings of the International Astronomical Union 15 巻 ( S352 ) 頁： 139 - 143 2020年6月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of the International Astronomical Union

We present ALMA [CII] line and far-infrared (FIR) continuum observations of seven z > 6 low-luminosity quasars (M1450 > -25 mag) discovered by our on-going Subaru Hyper Suprime-Cam survey. The [CII] line was detected in all targets with luminosities of ∼(2-10) × 108 Lo, about one order of magnitude smaller than optically luminous quasars. Also found was a wide scatter of FIR continuum luminosity, ranging from LFIR < 1011Lo to 1/42 × 1012Lo. With the [CII]-based dynamical mass, we suggest that a significant fraction of low-luminosity quasars are located on or even below the local Magorrian relation, particularly at the massive end of the galaxy mass distribution. This is a clear contrast to the previous finding that luminous quasars tend to have overmassive black holes relative to the relation. Our result is expected to show a less-biased nature of the early co-evolution of black holes and their host galaxies.

DOI： 10.1017/s1743921319009487

Panchromatic Analysis for Nature of HIgh-z galaxies Tool (PANHIT) 国際誌

Mawatari K., Inoue A.K., Yamanaka S., Hashimoto T., Tamura Y.

Proceedings of the International Astronomical Union 15 巻 ( S341 ) 頁： 285 - 286 2020年6月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of the International Astronomical Union

We have developed a new SED fitting tool specialized for frontier redshift galaxies. It is a common case for high-z galaxies that the available data are restricted to rich optical to near-infrared photometry and few far-infrared (FIR) data deep enough to detect the faint object (e.g., HST/WFC3 + Spitzer/IRAC + ALMA). In such situation, one cannot perform a complicated modeling of dust emission in FIR regime. We then adopt simple treatment for the dust emission using empirical LIRG templates. Instead, we adopt a sophisticated and physically motivated modeling for stellar and nebular emission parts in rest-frame UV-to-optical regime. Our new code fits not only broad band photometry but also spectral emission line flux. There is an option to fit observed SED with two templates with different physical properties. Our new code, PANHIT, is now in public, and was already applied to some high-z frontier galaxies.

DOI： 10.1017/s1743921319002606

Dust evolution in galaxies at z > 7 国際誌

Takeuchi T.T., Asano R.S., Nagasaki S., Nozawa T., Tamura Y., Mawatari K., Inoue A.K.

Proceedings of the International Astronomical Union 15 巻 ( S341 ) 頁： 312 - 313 2020年6月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of the International Astronomical Union

Recently huge amount of dust Mdust ≃ 106-7M in galaxies at z = 7-8 has been discovered by ALMA observations. The suggested timescale of the dust production was a few-several×108 yr, while the stellar mass was several × 109M . This amount of dust cannot be easily explained only by a supply from supernovae if we consider the dust destruction by reverse shocks. We propose that these values can be consistently explained if we take into account the grain growth in the interstellar medium (ISM). This scenario successfully reproduces the evolution of the dust mass, as well as the SFR, and stellar mass simultaneously. We conclude that even at such an early epoch of the Universe, the dust grain growth in the ISM plays a significant role in galaxies.

DOI： 10.1017/s1743921319003107

ALMA Observations of Molecular Gas in the Host Galaxies of Long-duration GRBs 国際誌

Hatsukade, Bunyo, Ohta, Kouji, Hashimoto, Tetsuya, Kohno, Kotaro, Nakanishi, Kouichiro, Niino, Yuu, Tamura, Yoichi

Yamada Conference LXXI: Gamma-ray Bursts in the Gravitational Wave Era 2019 頁： 157 - 159 2020年5月

DESHIMA on ASTE: On-Sky Responsivity Calibration of the Integrated Superconducting Spectrometer 査読有り

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

JOURNAL OF LOW TEMPERATURE PHYSICS 199 巻 ( 1-2 ) 頁： 231 - 239 2020年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Low Temperature Physics

We are developing an ultra-wideband spectroscopic instrument, DESHIMA (DEep Spectroscopic HIgh-redshift MApper), based on the technologies of an on-chip filter bank and microwave kinetic inductance detector (MKID) to investigate dusty starburst galaxies in the distant universe at millimeter and submillimeter wavelengths. An on-site experiment of DESHIMA was performed using the ASTE 10-m telescope. We established a responsivity model that converts frequency responses of the MKIDs to line-of-sight brightness temperature. We estimated two parameters of the responsivity model using a set of skydip data taken under various precipitable water vapor (PWV 0.4–3.0 mm) conditions for each MKID. The line-of-sight brightness temperature of sky is estimated using an atmospheric transmission model and the PWVs. As a result, we obtain an average temperature calibration uncertainty of 1 σ= 4 %, which is smaller than other photometric biases. In addition, the average forward efficiency of 0.88 in our responsivity model is consistent with the value expected from the geometrical support structure of the telescope. We also estimate line-of-sight PWVs of each skydip observation using the frequency response of MKIDs and confirm the consistency with PWVs reported by the Atacama Large Millimeter/submillimeter Array.

DOI： 10.1007/s10909-020-02338-0

その他リンク： http://link.springer.com/article/10.1007/s10909-020-02338-0/fulltext.html

ALMA uncovers the [C II] emission and warm dust continuum in a z=8.31 Lyman break galaxy 査読有り

Bakx Tom J. L. C., Tamura Yoichi, Hashimoto Takuya, Inoue Akio K., Lee Minju M., Mawatari Ken, Ota Kazuaki, Umehata Hideki, Zackrisson Erik, Hatsukade Bunyo, Kohno Kotaro, Matsuda Yuichi, Matsuo Hiroshi, Okamoto Takashi, Shibuya Takatoshi, Shimizu Ikkoh, Taniguchi Yoshiaki, Yoshida Naoki

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 493 巻 ( 3 ) 頁： 4294 - 4307 2020年4月

ALMA CO Observations of the Host Galaxies of Long-duration Gamma-Ray Bursts. I. Molecular Gas Scaling Relations 査読有り

Hatsukade Bunyo, Ohta Kouji, Hashimoto Tetsuya, Kohno Kotaro, Nakanishi Kouichiro, Niino Yuu, Tamura Yoichi

ASTROPHYSICAL JOURNAL 892 巻 ( 1 ) 頁： 42 - 42 2020年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astrophysical Journal

We present the results of CO observations toward 14 host galaxies of long-duration gamma-ray bursts (GRBs) at z = 0.1-2.5 by using the Atacama Large Millimeter/submillimeter Array. We successfully detected CO (3-2) or CO (4-3) emission in eight hosts (z = 0.3-2), which more than doubles the sample size of GRB hosts with CO detection. The derived molecular gas mass is M gas = (0.2-6) × 1010 M o assuming metallicity-dependent CO-to-H2 conversion factors. By using the largest sample of GRB hosts with molecular gas estimates (25 in total, of which 14 are CO detected), including results from the literature, we compared molecular gas properties with those of other star-forming galaxies (SFGs). The GRB hosts tend to have a higher molecular gas mass fraction (μ gas) and a shorter gas depletion timescale (t depl) as compared with other SFGs at similar redshifts, especially at z ≲ 1. This could be a common property of GRB hosts or an effect introduced by the selection of targets that are typically above the main-sequence line. To eliminate the effect of selection bias, we analyzed μ gas and t depl as a function of the distance from the main-sequence line (δMS). We find that the GRB hosts follow the same scaling relations as other SFGs, where μ gas increases and t depl decreases with increasing δMS. No molecular gas deficit is observed when compared to other SFGs of similar star formation rate and stellar mass. These findings suggest that the same star formation mechanism is expected to be happening in GRB hosts as in other SFGs.

DOI： 10.3847/1538-4357/ab7992

その他リンク： https://iopscience.iop.org/article/10.3847/1538-4357/ab7992

A new off-point-less observing method for millimeter and submillimeter spectroscopy with a frequency-modulating local oscillator 査読有り

Taniguchi A., Tamura Y., Kohno K., Takahashi S., Horigome O., Maekawa J., Sakai T., Kuno N., Minamidani T.

Publications of the Astronomical Society of Japan 72 巻 ( 1 ) 頁： 2 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Publications of the Astronomical Society of Japan

We propose a new observing method for single-dish millimeter and submillimeter spectroscopy using a heterodyne receiver equipped with a frequency-modulating local oscillator (FMLO). Unlike conventional switching methods, which extract astronomical signals by subtracting the reference spectra of off-sources from those of on-sources, the FMLO method does not need to obtain any off-source spectra; rather, it estimates them from the on-source spectra themselves. The principle uses high-dump-rate (10 Hz) spectroscopy with radio frequency modulation achieved by fast sweeping of a local oscillator of a heterodyne receiver. Because sky emission (i.e., off-source) fluctuates as 1/f and is spectrally correlated, it can be estimated and subtracted from time series spectra (a timestream) by principal component analysis. Meanwhile, astronomical signals remain in the timestream since they are modulated to a higher time-frequency domain. The FMLO method therefore achieves (1) a remarkably high observation efficiency, (2) reduced spectral baseline wiggles, and (3) software-based sideband separation. We developed an FMLO system for the Nobeyama 45\:m telescope and a data reduction procedure for it. Frequency modulation was realized by a tunable and programmable first local oscillator. With observations of Galactic sources, we demonstrate that the observation efficiency of the FMLO method is dramatically improved compared to conventional switching methods. Specifically, we find that the time to achieve the same noise level is reduced by a factor of 3.0 in single-pointed observations and by a factor of 1.2 in mapping observations. The FMLO method can be applied to observations of fainter (mK) spectral lines and larger (deg^{2}) mapping. It offers much more efficient and baseline-stable observations compared to conventional switching methods.

DOI： 10.1093/pasj/psz121

Large format imaging spectrograph for the Large Submillimeter Telescope (LST)

Kohno Kotaro, Kawabe Ryohei, Tamura Yoichi, Endo Akira, Baselmans Jochem J. A., Karatsu Kenichi, Inoue Akio, Moriwaki Kana, Hayatsu Natsuki H., Yoshida Naoki, Yoshimura Yuki, Hatsukade Bunyo, Umehata Hideki, Oshima Tai, Takekoshi Tatsuya, Taniguchi Akio, Klaassen Pamela, Mroczkowski Tony, Cicone Claudia, Bertoldi Frank, Dannerbauer Helmut, Tosaki Tomoka

MILLIMETER, SUBMILLIMETER, AND FAR-INFRARED DETECTORS AND INSTRUMENTATION FOR ASTRONOMY X 11453 巻頁： 114530N 2020年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering

We present a conceptual study of a large format imaging spectrograph for next-generation large (50-m class) single-dish telescopes, i.e., the Large Submillimeter Telescope (LST) and Atacama Large Aperture Submillimeter Telescope (AtLAST). Recent discoveries of high-redshift star-forming galaxies at z=8-9 and candidate quiescent galaxies at z∼6 indicate the onset of earliest star formation just a few 100 million years after the Big Bang (i.e., z = 12-15), and LST/AtLAST will provide a unique pathway to uncover spectroscopically-identified ''first forming galaxies'' in the pre-reionization era, once it will be equipped with a large format imaging spectrograph. We describe the preliminary of 3-band, medium resolution (R=2000) imaging spectrograph with ∼1.5 M detectors in total based on the KATANA concept (Karatsu et al.∼2019), which exploits technologies of the integrated superconducting spectrometer (ISS) and a large-format imaging array like A-MKID.

DOI： 10.1117/12.2561238

TiEMPO: Open-source time-dependent end-to-end model for simulating ground-based submillimeter astronomical observations

Huijten Esmee, Roelvink Yannick, Brackenhoff Stefanie A., Taniguchi Akio, Bakx Tom, Marthi Kaushal B., Zaalberg Stan, Baselmans Jochem J. A., Chin Kah Wuy, Huiting Robert, Karatsu Kenichi, Laguna Alejandro Pascual, Tamura Yoichi, Takekoshi Tatsuya, Yates Stephen J. C., van Hoven Maarten, Endo Akira

MILLIMETER, SUBMILLIMETER, AND FAR-INFRARED DETECTORS AND INSTRUMENTATION FOR ASTRONOMY X 11453 巻頁： 114533C 2020年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering

The next technological breakthrough in millimeter-submillimeter astronomy is 3D imaging spectrometry with wide instantaneous spectral bandwidths and wide fields of view. The total optimization of the focal-plane instrument, the telescope, the observing strategy, and the signal-processing software must enable efficient removal of foreground emission from the Earth's atmosphere, which is time-dependent and highly nonlinear in frequency. Here we present TiEMPO: Time-dependent End-To-end Model for Post-process Optimization of the DESHIMA spectrometer. TiEMPO utilizes a dynamical model of the atmosphere and parametrized models of the astronomical source, the telescope, the instrument, and the detector. The output of TiEMPO is a timestream of sky brightness temperature and detected power, which can be analyzed by standard signal-processing software. We first compare TiEMPO simulations with an on-sky measurement by the wideband DESHIMA spectrometer, and find good agreement in the noise power spectral density and sensitivity. We then use TiEMPO to simulate the detection of the line emission spectrum of a high-redshift galaxy using the DESHIMA 2.0 spectrometer in development. The TiEMPO model is open source. Its modular and parametrized design enables users to adapt it to design and optimize the end-To-end performance of spectroscopic and photometric instruments on existing and future telescopes.

DOI： 10.1117/12.2561014

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies 査読有り

Izumi Takuma, Onoue Masafusa, Matsuoka Yoshiki, Nagao Tohru, Strauss Michael A., Imanishi Masatoshi, Kashikawa Nobunari, Fujimoto Seiji, Kohno Kotaro, Toba Yoshiki, Umehata Hideki, Goto Tomotsugu, Ueda Yoshihiro, Shirakata Hikari, Silverman John D., Greene Jenny E., Harikane Yuichi, Hashimoto Yasuhiro, Ikarashi Soh, Iono Daisuke, Iwasawa Kazushi, Lee Chien-Hsiu, Minezaki Takeo, Nakanishi Kouichiro, Tamura Yoichi, Tang Ji-Jia, Taniguchi Akio

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 71 巻 ( 6 ) 2019年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Publications of the Astronomical Society of Japan

We present ALMA [C II] line and far-infrared (FIR) continuum observations of three z > 6 low-luminosity quasars (M1450 > –25 mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C II] line was detected in all three targets with luminosities of (2.4–9.5) × 108 L⊙, about one order of magnitude smaller than optically luminous (M1450 ≲ –25 mag) quasars. The FIR continuum luminosities range from < 9 × 1010 L⊙ (3 σ limit) to ∼2 × 1012 L⊙, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studied thus far show [C II]/FIR luminosity ratios similar to local star-forming galaxies. Using the [C II]-based dynamical mass (Mdyn) as a surrogate for bulge stellar mass (Mbulge), we find that a significant fraction of low-luminosity quasars are located on or even below the local MBH–Mbulge relation, particularly at the massive end of the galaxy mass distribution. In contrast, previous studies of optically luminous quasars have found that black holes are overmassive relative to the local relation. Given the low luminosities of our targets, we are exploring the nature of the early co-evolution of supermassive black holes and their hosts in a less biased way. Almost all of the quasars presented in this work are growing their black hole mass at a much higher pace at z ∼ 6 than the parallel growth model, in which supermassive black holes and their hosts grow simultaneously to match the local MBH–Mbulge relation at all redshifts. As the low-luminosity quasars appear to realize the local co-evolutionary relation even at z ∼ 6, they should have experienced vigorous starbursts prior to the currently observed quasar phase to catch up with the relation.

DOI： 10.1093/pasj/psz096

Detections of [O III] 88 mu m in two quasars in the reionization epoch 査読有り

Hashimoto Takuya, Inoue Akio K., Tamura Yoichi, Matsuo Hiroshi, Mawatari Ken, Yamaguchi Yuki

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 71 巻 ( 6 ) 2019年12月

First [N II]122 mu m Line Detection in a QSO-SMG Pair BRI 1202-0725 at z=4.69 査読有り

Lee Minju M., Nagao Tohru, De Breuck Carlos, Carniani Stefano, Cresci Giovanni, Hatsukade Bunyo, Kawabe Ryohei, Kohno Kotaro, Maiolino Roberto, Mannucci Filippo, Marconi Alessandro, Nakanishi Kouichiro, Saito Toshiki, Tamura Yoichi, Troncoso Paulina, Umehata Hideki, Yun Min

ASTROPHYSICAL JOURNAL LETTERS 883 巻 ( 2 ) 頁： L29 2019年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astrophysical Journal Letters

We report the first detection obtained with the Atacama Large Millimeter/submillimeter Array of the [N ii] 122 μm line emission from a galaxy group BRI 1202-0725 at z = 4.69 consisting of a quasi-stellar object (QSO) and a submillimeter-bright galaxy (SMG). Combining this with a detection of [N ii] 205 μm line in both galaxies, we constrain the electron densities of the ionized gas based on the line ratio of [N ii] 122/205. The derived electron densities are and cm-3 for the SMG and the QSO, respectively. The electron density of the SMG is similar to that of the Galactic Plane and to the average of the local spirals. However, higher electron densities (by up to a factor of three) could be possible for systematic uncertainties of the line flux estimates. The electron density of the QSO is comparable to high-z star-forming galaxies at z = 1.5-2.3, obtained using rest-frame optical lines and with the lower limits suggested from stacking analysis on lensed starbursts at z = 1-3.6 using the same tracer of [N ii]. Our results suggest a large scatter of electron densities in global scale at fixed star formation rates for extreme starbursts. The success of the [N ii] 122 μm and 205 μm detections at z = 4.69 demonstrates the power of future systematic surveys of extreme starbursts at z > 4 for probing the interstellar medium conditions and the effects on surrounding environments.

DOI： 10.3847/2041-8213/ab412e

Large Population of ALMA Galaxies at z>6 with Very High [OIII]88um to [CII]158um Flux Ratios: Evidence of Extremely High Ionization Parameter or PDR Deficit? 査読有り

Harikane, Yuichi, Ouchi, Masami, Inoue, Akio K., Matsuoka, Yoshiki, Tamura, Yoichi, Bakx, Tom, Fujimoto, Seiji, Moriwaki, Kana, Ono, Yoshiaki, Nagao, Tohru, Tadaki, Ken-ichi, Kojima, Takashi, Shibuya, Takatoshi, Egami, Eiichi, Ferrara, Andrea, Gallerani, Simona, Hashimoto, Takuya, Kohno, Kotaro, Matsuda, Yuichi, Matsuo, Hiroshi, Pallottini, Andrea, Sugahara, Yuma, Vallini, Livia

2019年10月

掲載種別：研究論文（学術雑誌）出版者・発行元：arXiv e-prints

We present our new ALMA observations targeting [OIII]88um, [CII]158um, [NII]122um, and dust continuum emission for three Lyman break galaxies at z=6.0293-6.2037 identified in the Subaru/Hyper Suprime-Cam survey. We clearly detect [OIII] and [CII] lines from all of the galaxies at 4.3-11.8sigma levels, and identify multi-band dust continuum emission in two of the three galaxies, allowing us to estimate infrared luminosities and dust temperatures simultaneously. In conjunction with previous ALMA observations for six galaxies at z>6, we confirm that all the nine z=6-9 galaxies have high [OIII]/[CII] ratios of L[OIII]/L[CII]~3-20, ~10 times higher than z~0 galaxies. We also find a positive correlation between the [OIII]/[CII] ratio and the Lya equivalent width (EW) at the >91% confidence level. We carefully investigate physical origins of the high [OIII]/[CII] ratios at z=6-9 using Cloudy, and find that high density of the interstellar medium, low C/O abundance ratio, and the cosmic microwave background attenuation are responsible to only a part of the z=6-9 galaxies. Instead, the observed high [OIII]/[CII] ratios are explained by 10-100 times higher ionization parameters or low photodissociation region (PDR) covering fractions of 0-10%, both of which are consistent with our [NII] observations. The latter scenario can be reproduced with a density bounded nebula with PDR deficit, which would enhance the Lya, Lyman continuum, and C+ ionizing photons escape from galaxies, consistent with the [OIII]/[CII]-Lya EW correlation we find. <P />...

A Radio-to-millimeter Census of Star-forming Galaxies in Protocluster 4C 23.56 at z=2.5: Global and Local Gas Kinematics 査読有り

Lee Minju M., Tanaka Ichi, Kawabe Ryohei, Aretxaga Itziar, Hatsukade Bunyo, Izumi Takuma, Kajisawa Masaru, Kodama Tadayuki, Kohno Kotaro, Nakanishi Kouichiro, Saito Toshiki, Tadaki Ken-ichi, Tamura Yoichi, Umehata Hideki, Zeballos Milagros

ASTROPHYSICAL JOURNAL 883 巻 ( 1 ) 頁： 92 2019年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astrophysical Journal

We present a study of the gas kinematics of star-forming galaxies associated with protocluster 4C 23.56 at z = 2.49 using 0.″4 resolution CO (4-3) data taken with ALMA. Eleven Hα emitters (HAEs) are detected in CO (4-3), including six HAEs that were previously detected in CO (3-2) at a coarser angular resolution. The detections in both CO lines are broadly consistent in the line widths and the redshifts, confirming both detections. With an increase in the number of spectroscopic redshifts, we confirm that the protocluster is composed of two merging groups with a total halo mass of log (M cl/M o) = 13.4-13.6, suggesting that the protocluster would evolve into a Virgo-like cluster (>1014 M o). We compare the CO line widths and the CO luminosities with other (proto)clusters (n gal = 91) and general field (n gal = 80) galaxies from other studies. The 4C 23.56 protocluster galaxies have CO line widths and luminosities comparable to other protocluster galaxies on average. On the other hand, the CO line widths are on average broader by ≈50% compared to field galaxies, while the median CO luminosities are similar. The broader line widths can be attributed to both effects of unresolved gas-rich mergers and/or compact gas distribution, which is supported by our limited but decent angular resolution observations and the size estimate of three galaxies. Based on these results, we argue that gas-rich mergers may play a role in the retention of the specific angular momentum to a value similar to that of field populations during cluster assembly, though we need to verify this with a larger number of samples.

DOI： 10.3847/1538-4357/ab3b5b

ADF22: Blind Detections of [C II] Line Emitters Shown to be Spurious 査読有り国際誌

Natsuki H. Hayatsu, R. J. Ivison, Paola Andreani, Hideki Umehata, Yuichi Matsuda, Naoki Yoshida, Kotaro Kohno, Bunyo Hatsukade, Akio K. Inoue, Yoichi Tamura, Tutomu T. Takeuchi, Seiji Fujimoto, Minju M. Lee, Tohru Nagao, Yiping Ao

Research Notes of the AAS 3 巻 ( 7 ) 頁： 97 2019年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Astronomical Society

We report Atacama Large Millimetre/submillimeter Array (ALMA) Cycle-5 follow-up observations of two candidate [CII] emitters at z ~ 6 in the ALMA deep field in SSA22 (ADF22). The candidates were detected blindly in a Cycle-2 ALMA survey covering ~ 5 square arcmins, with a single tuning, along with two CO lines associated with galaxies at lower redshifts. Various tests suggested at least one of the two > 6-sigma [CII] candidates should be robust (Hayatsu et al. 2017). Nevertheless, our new, deeper observations recover neither candidate, demonstrating a higher contamination rate than expected. The cause of the spurious detections is under investigation but at present it remains unclarified.

DOI： 10.3847/2515-5172/ab3228

ALMA Observations of Molecular Gas in the Host Galaxy of AT2018cow 査読有り

Morokuma-Matsui Kana, Morokuma Tomoki, Tominaga Nozomu, Hatsukade Bunyo, Hayashi Masao, Tamura Yoichi, Matsuda Yuichi, Motogi Kazuhito, Niinuma Kotaro, Konishi Masahiro

ASTROPHYSICAL JOURNAL LETTERS 879 巻 ( 1 ) 頁： L13 2019年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astrophysical Journal Letters

We investigate the molecular gas in and star formation properties of the host galaxy (CGCG 137-068) of a mysterious transient, AT2018cow, at kpc and larger scales, using archival band-3 data from the Atacama Large Millimeter/submillimeter Array (ALMA). AT2018cow is the nearest fast-evolving luminous transient (FELT); this is the first study unveiling molecular-gas properties of FELT hosts. The achieved rms and beam size are 0.21 mJy beam-1 at a velocity resolution of 40 km s-1 and 3.″66 × 2.″71 (1.1 kpc × 0.8 kpc), respectively. CO(J = 1-0) emission is successfully detected. The total molecular gas mass inferred from the CO data is (1.85 0.04) × 108 M o with the Milky Way CO-to-H2 conversion factor. The H2 column density at the AT2018cow site is estimated to be 8.6 × 1020 cm-2. The ALMA data reveal that (1) CGCG 137-068 is a normal star-forming (SF) dwarf galaxy in terms of its molecular gas and star formation properties, and (2) that AT2018cow is located between a CO peak and a blue star cluster. These properties suggest ongoing star formation and favor the explosion of a massive star as the progenitor of AT2018cow. We also find that CGCG 137-068 has a solar or super-solar metallicity. If the metallicity of the other FELT hosts is not higher than average, then some properties of SF dwarf galaxies other than metallicity may be related to FELTs.

DOI： 10.3847/2041-8213/ab2915

The absence of [C II] 158 mu m emission in spectroscopically confirmed galaxies at z > 8 査読有り

Laporte N., Katz H., Ellis R. S., Lagache G., Bauer F. E., Boone F., Inoue A. K., Hashimoto T., Matsuo H., Mawatari K., Tamura Y.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 487 巻 ( 1 ) 頁： L81 - L85 2019年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Monthly Notices of the Royal Astronomical Society: Letters

The scatter in the relationship between the strength of [C ii] 158 $mu$m emission and the star formation rate at high redshift has been the source of much recent interest. Although the relationship is well established locally, several intensely star-forming galaxies have been found whose [C ii] 158 $mu$m emission is either weak, absent, or spatially offset from the young stars. Here we present new ALMA data for the two most distant gravitationally lensed and spectroscopically confirmed galaxies, A2744-YD4 at z = 8.38 and MACS1149-JD1 at z = 9.11, both of which reveal intense [O iii] 88 $mu$m emission. In both cases we provide stringent upper limits on the presence of [C ii] 158 $mu$m with respect to [O iii] 88 $mu$m. We review possible explanations for this apparent redshift-dependent [C ii] deficit in the context of our recent hydrodynamical simulations. Our results highlight the importance of using several emission line diagnostics with ALMA to investigate the nature of the interstellar medium in early galaxies.

DOI： 10.1093/mnrasl/slz094

その他リンク： http://academic.oup.com/mnrasl/article-pdf/487/1/L81/28864236/slz094.pdf

ALMA 26 arcmin(2) Survey of GOODS-S at 1mm (ASAGAO): Near-infrared-dark Faint ALMA Sources 査読有り

Yamaguchi Yuki, Kohno Kotaro, Hatsukade Bunyo, Wang Tao, Yoshimura Yuki, Ao Yiping, Caputi Karina I, Dunlop James S., Egami Eiichi, Espada Daniel, Fujimoto Seiji, Hayatsu Natsuki H., Ivison Rob J., Kodama Tadayuki, Kusakabe Haruka, Nagao Tohru, Ouchi Masami, Rujopakarn Wiphu, Tadaki Ken-ichi, Tamura Yoichi, Ueda Yoshihiro, Umehata Hideki, Wang Wei-Hao, Yun Min S.

ASTROPHYSICAL JOURNAL 878 巻 ( 1 ) 頁： 73 2019年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Astrophysical Journal

We report detections of two 1.2 mm continuum sources (S 1.2 mm ∼ 0.6 mJy) without any counterparts in the deep H- and/or K-band image (i.e., K-band magnitude ≳26 mag). These near-infrared-dark faint millimeter sources are uncovered by ASAGAO, a deep and wide-field (≃26 arcmin2) Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm survey. One has a red IRAC (3.6 and 4.5 μm) counterpart, and the other has been independently detected at 850 and 870 μm using SCUBA2 and ALMA Band 7, respectively. Their optical-to-radio spectral energy distributions indicate that they can lie at z ≳ 3-5 and can be in the early phase of massive galaxy formation. Their contribution to the cosmic star formation rate density is estimated to be ∼1 ×10-3 M o yr-1 Mpc-3 if they lie somewhere in the redshift range of z ∼ 3-5. This value can be consistent with, or greater than, that of bright submillimeter galaxies (S 870 μm > 4.2 mJy) at z ∼ 3-5. We also uncover three more candidate near-infrared-dark faint ALMA sources without any counterparts (S 1.2 mm ∼ 0.45-0.86 mJy). These results show that an unbiased ALMA survey can reveal the dust-obscured star formation activities, which were missed in previous deep optical/near-infrared surveys.

DOI： 10.3847/1538-4357/ab0d22

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