研究者詳細 - 田村　陽一

論文 - 田村　陽一

分割表示 143 件中 101 - 120 件目／全件表示 >>

Molecular Gas Properties in the Host Galaxy of GRB 080207 査読有り

Hatsukade Bunyo, Hashimoto Tetsuya, Kohno Kotaro, Nakanishi Kouichiro, Ohta Kouji, Niino Yuu, Tamura Yoichi, Toth L. Viktor

ASTROPHYSICAL JOURNAL 876 巻 ( 2 ) 頁： 91 - 91 2019年5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(1-0) and CO(4-3) observations of the host galaxy of a long-duration gamma-ray burst GRB 080207 at z = 2.0858 by using the Karl G. Jansky Very Large Array and the Atacama Large Millimeter/submillimeter Array. The host is detected in CO(1-0) and CO(4-3), becoming the first case for a gamma-ray burst (GRB) host with more than two CO transitions detected combined with CO(2-1) and CO(3-2) in the literature. Adopting a metallicity-dependent CO-to-H2 conversion factor, we derive a molecular gas mass of M gas = 8.7 × 1010 M o, which places the host in a sequence of normal star-forming galaxies in an M gas-star formation rate (SFR) plane. A modified blackbody fit to the far-infrared-millimeter photometry results in a dust temperature of 37 K and a dust mass of M dust = 1.5 × 108 M o. The spatially resolved CO(4-3) observations allow us to examine the kinematics of the host. The CO velocity field shows a clear rotation and is reproduced by a rotation-dominated disk model with a rotation velocity of 350 km s-1 and a half-light radius of 2.4 kpc. The CO spectral line energy distribution derived from the four CO transitions is similar to that of starburst galaxies, suggesting a high excitation condition. Comparison of molecular gas properties between the host and normal (main-sequence) galaxies at similar redshifts shows that they share common properties such as gas mass fraction, gas depletion timescale, gas-to-dust ratio, location in the M gas-SFR (or surface density) relation, and kinematics, suggesting that long-duration GRBs can occur in normal star-forming environments at z ∼ 2.

DOI： 10.3847/1538-4357/ab1649

CNO Emission of an Unlensed Submillimeter Galaxy at z=4.3 査読有り

Tadaki Ken-ichi, Iono Daisuke, Hatsukade Bunyo, Kohno Kotaro, Lee Minju M., Matsuda Yuichi, Michiyama Tomonari, Nakanishi Kouichiro, Nagao Tohru, Saito Toshiki, Tamura Yoichi, Ueda Junko, Umehata Hideki

ASTROPHYSICAL JOURNAL 876 巻 ( 1 ) 頁： 1 2019年5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 from Atacama Large Millimeter/submillimeter Array observations of [N ii] 205 μm, [C ii] 158 μm, and [O iii] 88 μm lines in an unlensed submillimeter galaxy at z = 4.3, COSMOS-AzTEC-1, hosting a compact starburst core with an effective radius of ∼1 kpc. The [C ii] and [N ii] emission are spatially resolved in 0.″3-resolution (1 kpc in radius). The kinematic properties of the [N ii] emission are consistent with those of the CO(4-3) and [C ii] emission, suggesting that the ionized gas feels the same gravitational potential as the associated molecular gas and photodissociation regions (PDRs). On the other hand, the spatial extent is different among the lines and dust continuum: the [C ii] emitting gas is the most extended and the dust is the most compact, leading to a difference of the physical conditions in the interstellar medium. We derive the incident far-ultraviolet flux and the hydrogen gas density through PDR modeling by properly subtracting the contribution of ionized gas to the total [C ii] emission. The observed [C ii] emission is likely produced by dense PDRs with cm-3 and G 0 = 103.5-3.75 in the central 1 kpc region and cm-3 and G 0 = 103.25-3.5 in the central 3 kpc region. We have also successfully measured the line ratio of [O iii]/[N ii] in the central 3 kpc region of COSMOS-AzTEC-1 at z = 4.3, which is the highest redshift where both nitrogen and oxygen lines are detected. Under the most likely physical conditions, the measured luminosity ratio of L [O iii]/L [N ii] = 6.4 ±; 2.2 indicates a near solar metallicity with Z gas = 0.7-1.0 Z o, suggesting a chemically evolved system at z = 4.3.

DOI： 10.3847/1538-4357/ab1415

Exploration and characterization of the earliest epoch of galaxy formation: beyond the re-ionization era 査読有り国際誌

Kohno, Kotaro, Tamura, Yoichi, Inoue, Akio, Kawabe, Ryohei, Oshima, Tai, Hatsukade, Bunyo, Takekoshi, Tatsuya, Yoshimura, Yuki, Umehata, Hideki, Dannerbauer, Helmut, Cicone, Claudia, Bertoldi, Frank

Astro2020: Decadal Survey on Astronomy and Astrophysics 2019年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

Recent ALMA detection of the bright [OIII] 88 um line at z = 9.11, indicates the onset of star formation at z 15. In order to uncover a large number of z=10-15 galaxies, we argue two possible pathways: (1) a blind spectroscopic survey of [OIII] 88 um line emitters, and (2) a high-cadence survey of transient sources to catch the pop-III GRBs. <P />...

The case for a 'sub-millimeter SDSS': a 3D map of galaxy evolution to z 10 査読有り国際誌

Geach, James, Banerji, Manda, Bertoldi, Frank, Bethermin, Matthieu, Casey, Caitlin M., Chen, Chian-Chou, Clements, David L., Cicone, Claudia, Combes, Francoise, Conselice, Christopher, Cooray, Asantha, Coppin, Kristen, Daddi, Emanuele, Dannerbauer, Helmut, Dave, Romeel, Doherty, Matthew, Dunlop, James S., Edge, Alastair, Farrah, Duncan, Franco, Maximilien, Fuller, Gary, Garratt, Tracy, Gear, Walter, Greve, Thomas R., Hatziminaoglou, Evanthia, Hayward, Christopher C., Ivison, Rob J., Kawabe, Ryohei, Klaassen, Pamela, Knudsen, Kirsten K., Kohno, Kotaro, Koprowski, Maciej, Lagos, Claudia D. P., Magdis, Georgios E., Magnelli, Benjamin, McGee, Sean L., Michalowski, Michal, Mroczkowski, Tony, Noroozian, Omid, Narayanan, Desika, Oliver, Seb, Riechers, Dominik, Rujopakarn, Wiphu, Scott, Douglas, Serjeant, Stephen, Smith, Matthew W. L., Swinbank, Mark, Tamura, Yoichi, van der Werf, Paul, van Kampen, Eelco, Verma, Aprajita, Vieira, Joaquin, Wagg, Jeff, Walter, Fabian, Wang, Lingyu, Wootten, Al, Yun, Min S.

Bulletin of the American Astronomical Society 2019年5月

Mapping Galaxy Clusters in the Distant Universe 査読有り国際誌

Dannerbauer, Helmut, van Kampen, Eelco, Afonso, Jose, Andreani, Paola, Battaia, Fabrizio Arrigoni, Bertoldi, Frank, Casey, Caitlin, Chen, Chian-Chou, Clements, David L., De Breuck, Carlos, Frye, Brenda, Geach, James, Harrington, Kevin, Hayashi, Masao, Jin, Shuowen, Klaassen, Pamela, Kohno, Kotaro, Lehnert, Matthew D., Matute, Israel, Mroczkowski, Tony, Noble, Allison, Pappalardo, Ciro, Tamura, Yoichi, Zavala, Jorge

Bulletin of the American Astronomical Society 2019年5月

Environmental impacts on molecular gas in protocluster galaxies at z similar to 2 査読有り

Tadaki Ken-ichi, Kodama Tadayuki, Hayashi Masao, Shimakawa Rhythm, Koyama Yusei, Lee Minju, Tanaka Ichi, Hatsukade Bunyo, Iono Daisuke, Kohno Kotaro, Matsuda Yuichi, Suzuki Tomoko L., Tamura Yoichi, Toshikawa Jun, Umehata Hideki

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 71 巻 ( 2 ) 頁： 40 2019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：Publications of the Astronomical Society of Japan

We present the results from ALMA CO(3-2) observations of 66 Hα-selected galaxies in three protoclusters around radio galaxies: PKS 1138-262 (z = 2.16), USS 1558-003 (z = 2.53), and 4C 23.56 (z = 2.49). The pointing areas have an overdensity of ∼100 compared to the mean surface number density of galaxies in field environments. We detect the CO emission line in 16 star-forming galaxies, including six previously published galaxies, to measure the molecular gas mass. In the stellar mass range of 10.5 < log (Mstar/M⊙) < 11.0, the protocluster galaxies have larger gas mass fractions and longer gas depletion timescales compared to the scaling relations established for field galaxies. On the other hand, the amounts of molecular gas in more massive galaxies with log (Mstar/M⊙) > 11.0 are comparable in mass to the scaling relation, or smaller. Our results suggest that the environmental effects on gas properties are mass dependent: in high-density environments, gas accretion through cosmic filaments is accelerated in less massive galaxies, while this is suppressed in the most massive system.

DOI： 10.1093/pasj/psz005

The Excitation State of Galactic Diffuse Molecular Gas, Investigated with ALMA Observations of Multi-transition Absorption Lines 査読有り

Ando Ryo, Kohno Kotaro, Umehata Hideki, Izumi Takuma, Ishii Shun, Nishimura Yuri, Sorai Kazuo, Tosaki Tomoka, Taniguchi Akio, Tamura Yoichi

ASTROPHYSICAL JOURNAL 871 巻 ( 2 ) 2019年2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 Atacama Large Millimeter/submillimeter Array (ALMA) observations of 243-263 GHz absorption lines from Galactic diffuse molecular gas seen against three extragalactic radio-loud objects, J1717-337, J1625-254, and NRAO530. No significant absorption features were detected in our new sensitive ALMA Band 6 (λ ≃ 1.2 mm) spectra (1σ ≃ 2-4 mJy beam -1 with a velocity resolution of 1 km s -1 ), despite the fact that the obtained spectra cover the line frequencies of c-C 3 H 2 , CS, H 13 CN, HCO, H 13 CO + , SiO, and C 2 H, and that the lower transition absorption lines of these molecular species have been detected in ALMA Band 3 (λ ≃ 3 mm) observations toward these three Galactic molecular absorption systems. By combining the upper limits of the higher transitions that we obtain in this study and the archival detections of the lower transitions, we constrain the excitation temperatures of these species in the Galactic diffuse medium to be below 10 K, in spite of their PDR-like chemical states, where elevated column density ratios of HCO to H 13 CO + are previously reported. These constraints are in line with the widely accepted view of the diffuse molecular clouds, where the molecular excitation is almost in equilibrium with the cosmic microwave background, although its kinetic temperature can be a few tens of Kelvin. Molecular abundance patterns seem to be similar in the Galactic diffuse gas and nearby active galaxies observed with a kpc-scale beam, suggesting the importance of observations with a parsec-scale resolution, which can resolve individual molecular clouds.

DOI： 10.3847/1538-4357/aafa6f

ALMA twenty-six arcmin<SUP>2</SUP> survey of GOODS-S at one millimeter (ASAGAO): Source catalog and number counts 査読有り

Hatsukade Bunyo, Kohno Kotaro, Yamaguchi Yuki, Umehata Hideki, Ao Yiping, Aretxaga Itziar, Caputi Karina I., Dunlop James S., Egami Eiichi, Espada Daniel, Fujimoto Seiji, Hayatsu Natsuki H., Hughes David H., Ikarashi Soh, Iono Daisuke, Ivison Rob J., Kawabe Ryohei, Kodama Tadayuki, Lee Minju, Matsuda Yuichi, Nakanishi Kouichiro, Ohta Kouji, Ouchi Masami, Rujopakarn Wiphu, Suzuki Tomoko, Tamura Yoichi, Ueda Yoshihiro, Wang Tao, Wang Wei-Hao, Wilson Grant W., Yoshimura Yuki, Yun Min S.

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 70 巻 ( 6 ) 頁： 239 - 240 2018年12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 present the survey design, data reduction, construction of images, and source catalog of the Atacama Large Millimeter/submillimeter Array (ALMA) twenty-six arcmin2 survey of GOODS-S at one millimeter (ASAGAO). ASAGAO is a deep (1 σ depth ∼ 61 μJy beam−1 for a 250 kλ-tapered map with a synthesized beam size of 0.51 × 0.45) and wide area (26 arcmin2) survey on a contiguous field at 1.2 mm. By combining with ALMA archival data in the GOODS-South field, we obtained a deeper map in the same region (1 σ depth ∼ 30 μJy beam−1 for a deep region with a 250 kλ-taper, and a synthesized beam size of 0.59 × 0.53), providing the largest sample of sources (25 sources at ≥5.0 σ, 45 sources at ≥4.5 σ) among ALMA blank-field surveys to date. The number counts show that 52+−118 % of the extragalactic background light at 1.2 mm is resolved into discrete sources at S1.2 mm > 135 μJy. We create infrared (IR) luminosity functions (LFs) in the redshift range of z = 1–3 from the ASAGAO sources with Ks-band counterparts, and constrain the faintest luminosity of the LF at 2.0 < z < 3.0. The LFs are consistent with previous results based on other ALMA and SCUBA-2 observations, which suggest a positive luminosity evolution and negative density evolution with increasing redshift. We find that obscured star-formation of sources with IR luminosities of log (LIR/L) 11.8 account for ≈60%–90% of the z ∼ 2 cosmic star-formation rate density.

DOI： 10.1093/pasj/psy104

Development of Multi-temperature Calibrator for the TES Bolometer Camera: System Design 査読有り

Takekoshi Tatsuya, Ohtawara Kazushige, Oshima Tai, Ishii Shun, Izumi Natsuko, Izumi Takuma, Yamaguchi Masayuki, Suzuki Shunta, Muraoka Kazuyuki, Hirota Akihiko, Saito Fumiaki, Nakatsubo Shunichi, Kouchi Akira, Ito Tetsuya, Uemizu Kazunori, Fujii Yasunori, Tamura Yoichi, Kohno Kotaro, Kawabe Ryohei

JOURNAL OF LOW TEMPERATURE PHYSICS 193 巻 ( 5-6 ) 頁： 1003 - 1009 2018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：Journal of Low Temperature Physics

We developed a simple add-on, cryogen-free, and low-power consumption calibrator for a new transition-edge sensor (TES) bolometer camera mounted on the ASTE 10-m telescope. To measure the responsivity of the TES bolometers and accurately correct for the nonlinearity and atmospheric extinction, we designed a motor-driven rotating filter wheel system installed in front of the cryostat window. This calibrator is required to cover the loading power under various atmospheric conditions, which corresponds to precipitable water vapor (PWV) of 0.5–4 mm. For this range of PWV, 25–100 K blackbodies are necessary for the observing bands of 1.1 and 0.85 mm. To simulate the temperature range, bolometers in the cryostat are also optically coupled to the low-temperature stage (< 4 K) inside the cryostat by spherical mirrors. In addition, we used moderately absorptive polystyrene plates that are placed between a spherical mirror and the cryostat window. Various combinations of filters result in eight different temperatures by the filter wheel system and simulate the atmospheric emission under various weather conditions at the ASTE site.

DOI： 10.1007/s10909-018-1916-1

Development of Multi-temperature Calibrator for the TES Bolometer Camera: Deployment at ASTE 査読有り

Oshima Tai, Ohtawara Kazushige, Takekoshi Tatsuya, Ishii Shun, Izumi Natsuko, Izumi Takuma, Yamaguchi Masayuki, Suzuki Shunta, Muraoka Kazuyuki, Hirota Akihiko, Saito Fumiaki, Nakatsubo Shunichi, Kouchi Akira, Ito Tetsuya, Uemizu Kazunori, Fujii Yasunori, Tamura Yoichi, Kohno Kotaro, Kawabe Ryohei

JOURNAL OF LOW TEMPERATURE PHYSICS 193 巻 ( 5-6 ) 頁： 996 - 1002 2018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：Journal of Low Temperature Physics

We developed and deployed a simple add-on multi-temperature calibrator for our multicolor transition edge sensor (TES) bolometer camera aimed at simultaneous observation with observing wavelengths of 1.1 and 0.85 mm. To cover the power loading level from the atmospheric emission corresponding to precipitable water vapor (PWV) of 0.5–4 mm, the calibrator consists of spherical mirrors to show the low-temperature stages of the cryostat and filters with moderate opacity to mimic the eight-temperature cold blackbodies. The loading powers introduced by each filter were self-calibrated by measuring the load curves of the TES bolometers when a filter was placed in front of the cryostat window. Each science observation was preceded by the calibration process, which measures the response of the TES bolometers to the atmosphere and filters of various opacities. Then, the responsivities of TES bolometers were derived to convert their output signal to the loading power and correct for the nonlinearity inherent in its response. Furthermore, the loading power falling on the TES bolometers from atmospheric emission measured at various PWV was in good correlation with the PWV measured with the radiometer, which enables the atmospheric extinction correction by fast and sensitive bolometers compared to the available radiometers with the modest sampling speeds.

DOI： 10.1007/s10909-018-2009-x

The distribution and physical properties of high-redshift [O III] emitters in a cosmological hydrodynamics simulation 査読有り

Moriwaki Kana, Yoshida Naoki, Shimizu Ikkoh, Harikane Yuichi, Matsuda Yuichi, Matsuo Hiroshi, Hashimoto Takuya, Inoue Akio K., Tamura Yoichi, Nagao Tohru

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 481 巻 ( 1 ) 頁： L84 - L88 2018年11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

Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected far-infrared emission lines such as the [OIII] 88μm line from galaxies at z ~ 7-9. We use a cosmological simulation of galaxy formation to study the physical properties of [O III] 88μm emitters. In a comoving volume of 50 h-1 Mpc on a side, we locate 34 galaxies with stellar masses greater than 108 M⊙ at z = 9, and more than 270 such galaxies at z = 7. We calculate the [O III] 88μm luminosities (LOIII,88) by combining a physical model of HII regions with emission line calculations using the photoionization code CLOUDY.We show that the resulting LOIII,88, for a given star formation rate, is slightly higher than predicted from the empirical relation for local galaxies, and is consistent with recent observations of galaxies at redshifts 7-9. Bright [O III] emitters with LOIII,88 > 108 L⊙ have star formation rates higher than 3M⊙ yr-1, and the typical metallicity is ~0.1Z⊙. The galaxies are hosted by dark matter haloes with masses greater than 1011M⊙. We propose to use the [OIII] 5007Å line, to be detected by James Webb Space Telescope, to study the properties of galaxies whose [OIII] 88 μm line emission has been already detected with ALMA.

DOI： 10.1093/mnrasl/sly167

Extremely Dense Cores Associated with Chandra Sources in Ophiuchus A: Forming Brown Dwarfs Unveiled? 査読有り

Kawabe Ryohei, Hara Chihomi, Nakamura Fumitaka, Saigo Kazuya, Kamazaki Takeshi, Shimajiri Yoshito, Tomida Kengo, Takakuwa Shigehisa, Tsuboi Yohko, Machida Masahiro N., Di Francesco James, Friesen Rachel, Hirano Naomi, Oasa Yumiko, Tamura Motohide, Tamura Yoichi, Tsukagoshi Takashi, Wilner David

ASTROPHYSICAL JOURNAL 866 巻 ( 2 ) 2018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

On the basis of various data such as ALMA, JVLA, Chandra, Herschel, and Spitzer, we confirmed that two protostellar candidates in Oph A are bona fide protostars or proto-brown dwarfs (proto-BDs) in extremely early evolutionary stages. Both objects are barely visible across infrared (IR; i.e., near-IR to far-IR) bands. The physical nature of the cores is very similar to that expected in first hydrostatic cores (FHSCs), objects theoretically predicted in the evolutionary phase prior to stellar core formation with gas densities of ∼1011-12 cm-3. This suggests that the evolutionary stage is close to the FHSC formation phase. The two objects are associated with faint X-ray sources, suggesting that they are in very early phase of stellar core formation with magnetic activity. In addition, we found the CO outflow components around both sources, which may originate from the young outflows driven by these sources. The masses of these objects are calculated to be ∼0.01-0.03 M o from the dust continuum emission. These physical properties are consistent with that expected from the numerical model of forming brown dwarfs. These facts (the X-ray detection, CO outflow association, and FHSC-like spectral energy distributions) strongly indicate that the two objects are proto-BDs or will be in the very early phase of protostars, which will evolve to more massive protostars if they gain enough mass from their surroundings. The ages of these two objects are likely to be within ∼103 years after the protostellar core (or second core) formation, taking into account the outflow dynamical times (≲500 years).

DOI： 10.3847/1538-4357/aae153

Detections of [OIII] 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

2018年10月

掲載種別：研究論文（学術雑誌）出版者・発行元：arXiv e-prints

With the Atacama Large Millimeter/sub-millimeter Array (ALMA), we report detections of the far-infrared (FIR) [OIII] 88 $\mu$m line and the underlying dust continuum in the two quasars in the reionization epoch, J205406.48-000514.8 (hereafter J2054-0005) at $z=6.0391\pm0.0002$ and J231038.88+185519.7 (hereafter J2310+1855) at $z=6.0035\pm0.0007$. The [OIII] luminosity of J2054-0005 and J2310+1855 are $L_{\rm [OIII]} = (6.8\pm0.6) \times 10^{9}$ and $(2.4\pm0.6) \times 10^{9}$ $L_{\rm \odot}$, corresponding to $\approx$ 0.05\%\ and 0.01\%\ of the total infrared luminosity, $L_{\rm TIR}$, respectively. Combining these [OIII] luminosities with [CII] 158 $\mu$m luminosities in the literature, we find that J2054-0005 and J2310+1855 have the [OIII]-to-[CII] luminosity ratio of $2.1\pm0.4$ and $0.3\pm0.1$, respectively, the latter of which is the lowest among objects so far reported at $z>6$. Combining [OIII] observations at $z\approx6-9$ from our study and the literature, we identify the [OIII] line deficit: objects with larger $L_{\rm TIR}$ have lower $L_{\rm [OIII]}$-to-$L_{\rm TIR}$ ratios. Furthermore, we also find that the anti-correlation is shifted toward higher $L_{\rm TIR}$ value when compared to the local [OIII] line deficit. <P />...

AzTEC 1.1 mm observations of high-z protocluster environments: SMG overdensities and misalignment between AGN jets and SMG distribution 査読有り国際誌

Zeballos, M., Aretxaga, I., Hughes, D. H., Humphrey, A., Wilson, G. W., Austermann, J., Dunlop, J. S., Ezawa, H., Ferrusca, D., Hatsukade, B., Ivison, R. J., Kawabe, R., Kim, S., Kodama, T., Kohno, K., Montaña, A., Nakanishi, K., Plionis, M., Sánchez-Argüelles, D., Stevens, J. A., Tamura, Y., Velazquez, M., Yun, M. S.

Monthly Notices of the Royal Astronomical Society 2018年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

We present observations at 1.1 mm towards 16 powerful radio galaxies and a radio-quiet quasar at 0.5 < z < 6.3 acquired with the AzTEC camera mounted at the James Clerk Maxwell Telescope and Atacama Submillimeter Telescope Experiment to study the spatial distribution of submillimetre galaxies (SMGs) towards possible protocluster regions. The survey covers a total area of 1.01 sq deg with rms depths of 0.52-1.44 mJy and detects 728 sources above 3σ. We find overdensities of a factor of ̃2 in the source counts of three individual fields (4C+23.56, PKS1138-262, and MRC0355-037) over areas of ̃200 sq deg. When combining all fields, the source-count analysis finds an overdensity that reaches a factor ≳3 at S<SUB>1.1mm</SUB> ≥ 4 mJy covering a 1.5-arcmin-radius area centred on the active galactic nucleus. The large size of our maps allows us to establish that beyond a radius of 1.5 arcmin, the radial surface density of SMGs falls to that of a blank field. In addition, we find a trend for SMGs to align closely to a perpendicular direction with respect to the radio jets of the powerful central radio galaxies (73_{+13}^{-14} deg). This misalignment is found over projected comoving scales of 4-20 Mpc, departs from perfect alignment (0 deg) by ̃5σ, and apparently has no dependence on SMG luminosity. Under the assumption that the AzTEC sources are at the redshift of the central radio galaxy, the misalignment reported here can be interpreted as SMGs preferentially inhabiting mass-dominant filaments funnelling material towards the protoclusters, which are also the parent structures of the radio galaxies. <P />...

DOI： 10.1093/mnras/sty1714

The gravitationally unstable gas disk of a starburst galaxy 12 billion years ago 査読有り

Tadaki K., Iono D., Yun M. S., Aretxaga I., Hatsukade B., Hughes D. H., Ikarashi S., Izumi T., Kawabe R., Kohno K., Lee M., Matsuda Y., Nakanishi K., Saito T., Tamura Y., Ueda J., Umehata H., Wilson G. W., Michiyama T., Ando M., Kamieneski P.

NATURE 560 巻 ( 7720 ) 頁： 613 - + 2018年8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：Nature

Galaxies in the early Universe that are bright at submillimetre wavelengths (submillimetre-bright galaxies) are forming stars at a rate roughly 1,000 times higher than the Milky Way. A large fraction of the new stars form in the central kiloparsec of the galaxy1–3, a region that is comparable in size to the massive, quiescent galaxies found at the peak of cosmic star-formation history4 and the cores of present-day giant elliptical galaxies. The physical and kinematic properties inside these compact starburst cores are poorly understood because probing them at relevant spatial scales requires extremely high angular resolution. Here we report observations with a linear resolution of 550 parsecs of gas and dust in an unlensed, submillimetre-bright galaxy at a redshift of z = 4.3, when the Universe was less than two billion years old. We resolve the spatial and kinematic structure of the molecular gas inside the heavily dust-obscured core and show that the underlying gas disk is clumpy and rotationally supported (that is, its rotation velocity is larger than the velocity dispersion). Our analysis of the molecular gas mass per unit area suggests that the starburst disk is gravitationally unstable, which implies that the self-gravity of the gas is stronger than the differential rotation of the disk and the internal pressure due to stellar-radiation feedback. As a result of the gravitational instability in the disk, the molecular gas would be consumed by star formation on a timescale of 100 million years, which is comparable to gas depletion times in merging starburst galaxies5.

DOI： 10.1038/s41586-018-0443-1

ALMA deep field in SSA22: Survey design and source catalog of a 20 arcmin<SUP>2</SUP> survey at 1.1 mm 査読有り

Umehata Hideki, Hatsukade Bunyo, Smail Ian, Alexander David M., Ivison Rob J., Matsuda Yuichi, Tamura Yoichi, Kohno Kotaro, Kato Yuta, Hayatsu Natsuki H., Kubo Mariko, Ikarashi Soh

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 70 巻 ( 4 ) 2018年8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

To search for dust-obscured star-formation activity in the early Universe, it is essential to obtain a deep and wide submillimeter/millimeter map. The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled us to obtain such maps with sufficiently high spatial resolution to be free from source confusion. We present a new 1.1 mm-wave map obtained by ALMA in the SSA22 field. The field contains a remarkable proto-cluster at z = 3.09; therefore, it is an ideal region to investigate the role of a large-scale cosmic web on dust-obscured star formation. The typical 1σ depth of our map is 73 μJy beam−1 with a 0.5 resolution. Combining the present survey with earlier, archived observations, we map an area of 20 arcmin2 (71 comoving Mpc2 at z = 3.09). Within the combined survey area we have detected 35 sources at a signal-to-noise ratio (S/N) >5, with flux densities of S1.1mm = 0.43-5.6 mJy, equivalent to star-formation rates of 100-1000 M yr−1 at z = 3.09, for a Chabrier initial mass function: 17 sources out of 35 are new detections. The cumulative number counts show an excess by a factor of three to five compared to blank fields. The excess suggests enhanced, dust-enshrouded star-formation activity in the proto-cluster on a 10 comoving Mpc scale, indicating accelerated galaxy evolution in this overdense region.

DOI： 10.1093/pasj/psy065

ALMA 26 Arcmin<SUP>2</SUP> Survey of GOODS-S at One Millimeter (ASAGAO): Average Morphology of High-<i>z</i> Dusty Star-forming Galaxies in an Exponential Disk (<i>n</i> ≃ 1) 査読有り

Fujimoto Seiji, Ouchi Masami, Kohno Kotaro, Yamaguchi Yuki, Hatsukade Bunyo, Ueda Yoshihiro, Shibuya Takatoshi, Inoue Shigeki, Oogi Taira, Toft Sune, Gomez-Guijarro Carlos, Wang Tao, Espada Daniel, Nagao Tohru, Tanaka Ichi, Ao Yiping, Umehata Hideki, Taniguchi Yoshiaki, Nakanishi Kouichiro, Rujopakarn Wiphu, Ivison R. J., Wang Wei-hao, Lee Minju M., Tadaki Ken-ichi, Tamura Yoichi, Dunlop J. S.

ASTROPHYSICAL JOURNAL 861 巻 ( 1 ) 2018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：Astrophysical Journal

We present morphological properties of dusty star-forming galaxies at z = 1-3 determined with the high-resolution (FWHM ∼ 0.″19) Atacama Large Milllimeter/submillimeter Array (ALMA) 1 mm map of our ASAGAO survey covering a 26 arcmin2 area in GOODS-S. In conjunction with the ALMA archival data, our sample consists of 45 ALMA sources with infrared luminosity (L IR) range of ∼1011-1013 L o. To obtain an average rest-frame far-infrared (FIR) profile, we perform individual measurements and careful stacking of the ALMA sources using the uv-visibility method that includes positional-uncertainty and smoothing-effect evaluations through Monte Carlo simulations. We find that our sample has an average FIR-wavelength Sérsic index and effective radius of n FIR = 1.2 ± 0.2 and R e,FIR = 1.0-1.3 kpc, respectively, additionally with a point-source component at the center, indicative of the existence of active galactic nuclei. The average FIR profile agrees with a morphology of an exponential disk clearly distinguished from a de Vaucouleurs spheroidal profile (Sérsic index of 4). We also examine the rest-frame optical Sérsic index n opt and effective radius R e,opt with deep Hubble Space Telescope (HST) images. Interestingly, we obtain n opt = 0.9 ± 0.3 (≃n FIR) and R e,opt = 3.2 ± 0.6 kpc (>R e,FIR), suggesting that the dusty disk-like structure is embedded within a larger stellar disk. The rest-frame UV and FIR data of HST and ALMA provide us with a radial profile of the total star formation rate (SFR), where the infrared SFR dominates over the UV SFR at the center. Under the assumption of a constant SFR, a compact stellar distribution in z ∼ 1-2 compact quiescent galaxies (cQGs) is well reproduced, while a spheroidal stellar morphology of cQGs (n opt = 4) is not, suggestive of other important mechanism(s) such as dynamical dissipation.

DOI： 10.3847/1538-4357/aac6c4

Laboratory performance evaluation of the mid-infrared camera and spectrograph MIMIZUKU for the TAO 6.5-m telescope

Kamizuka, Takafumi, Uchiyama, Masahito S, Yamaguchi, Jumpei, Mori, Tomohiro, Ohsawa, Ryou, Yoshida, Yutaka, Sako, Shigeyuki, Miyata, Takashi, Asano, Kentaro, Uchiyama, Mizuho, Sakon, Itsuki, Onaka, Takashi, Kataza, Hirokazu, Aoki, Tsutomu, Doi, Mamoru, Hatsukade, Bunyo, Kato, Natsuko, Kohno, Kotaro, Konishi, Masahiro, Minezaki, Takeo, Morokuma, Tomoki, Motohara, Kentaro, Soyano, Takao, Takahashi, Hidenori, Tanabe, Toshihiko, Tanaka, Masuo, Tarusawa, Ken'ichi, Tamura, Yoichi, Yoichi, Koshida, Shintaro, Terao, Yasunori, Ohashi, Hirofumi, Kono, Yukihiro, Kushibiki, Kosuke, Yoshii, Yuzuru

Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series 10702 巻頁： 107022H 2018年7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 SPIE - The International Society for Optical Engineering

The Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU) is a mid-infrared camera and spectrograph developed as a first-generation instrument on the University of Tokyo Atacama Observatory (TAO) 6.5-m telescope. MIMIZUKU covers a wide wavelength range from 2 to 38 μm and has a unique optical device called Field Stacker which realizes accurate calibration of variable atmospheric transmittance with a few percent accuracy. By utilizing these capabilities, MIMIZUKU realizes mid-infrared long-term monitoring, which has not been challenged well. MIMIZUKU has three optical channels, called NIR, MIR-S, and MIR-L, to realize the wide wavelength coverage. The MIR-S channel, which covers 6.8-26 μm, has been completed by now. We are planning to perform engineering observations with this channel at the Subaru telescope before the completion of the TAO 6.5-m telescope. In this paper, we report the results of the laboratory tests to evaluate the optical and detector performances of the MIR-S channel. As a result, we confirmed a pixel scale of 0.12 arcsec/pix and a vignetting- free field of view of 2./0 1./8. The instrument throughputs for imaging modes are measured to be 20-30%. Those for N - and Q -band spectroscopy modes are 17 and 5%, respectively. As for the detector performance, we derived the quantum efficiency to be 40-50% in the mid-infrared wavelength region and measured the readout noise to be 3000-6000 electrons, which are larger than the spec value. It was found that this large readout noise degrades the sensitivity of MIMIZUKU by a factor of two.

DOI： 10.1117/12.2312443

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). III. Star formation properties of the host galaxies at z greater than or similar to 6 studied with ALMA 査読有り

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

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 70 巻 ( 3 ) 2018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：Publications of the Astronomical Society of Japan

We present our ALMA Cycle 4 measurements of the [C II] emission line and the underlying far-infrared (FIR) continuum emission from four optically low-luminosity (M1450 > -25) quasars at z ≳ 6 discovered by the Subaru Hyper Suprime Cam (HSC) survey. The [C II] line and FIR continuum luminosities lie in the ranges L[C II] = (3.8-10.2) × 108 L· and LFIR = (1.2-2.0) × 1011 L·, which are at least one order of magnitude smaller than those of optically-luminous quasars at z ≳ 6. We estimate the star formation rates (SFRs) of our targets as ≲ 23-40 M· yr-1. Their line and continuum-emitting regions are marginally resolved, and found to be comparable in size to those of optically-luminous quasars, indicating that their SFR or likely gas mass surface densities (key controlling parameter of mass accretion) are accordingly different. The L[C II]/LFIR ratios of the hosts, ≲ (2.2- 8.7) × 10-3, are fully consistent with local star-forming galaxies. Using the [C II] dynamics, we derived their dynamical masses within a radius of 1.5-2.5 kpc as ≲ (1.4-8.2) × 1010 M·. By interpreting these masses as stellar ones, we suggest that these faint quasar hosts are on or even below the star-forming main sequence at z ∼ 6, i.e., they appear to be transforming into quiescent galaxies. This is in contrast to the optically-luminous quasars at those redshifts, which show starburst-like properties. Finally, we find that the ratios of black hole mass to host galaxy dynamical mass of most of the low-luminosity quasars, including the HSC ones, are consistent with the local value. The mass ratios of the HSC quasars can be reproduced by a semi-analytical model that assumes merger-induced black hole host galaxy evolution.

DOI： 10.1093/pasj/psy026

Obscured Star Formation in the Host Galaxies of Superluminous Supernovae 査読有り

Hatsukade B., Tominaga N., Hayashi M., Konishi M., Matsuda Y., Morokuma T., Morokuma-Matsui K., Motogi K., Niinuma K., Tamura Y.

ASTROPHYSICAL JOURNAL 857 巻 ( 1 ) 頁： 72 - 72 2018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：Astrophysical Journal

We present the results of 3 GHz radio continuum observations of the eight host galaxies of superluminous supernovae (SLSNe) at 0.1 < z < 0.3 by using the Karl G. Jansky Very Large Array. Four host galaxies are detected significantly, and two of them are found to have high star formation rates (SFRs > 20 M o yr-1) derived from radio emission, making them the most intensely star-forming host galaxies among SLSN host galaxies. We compare radio SFRs and optical SFRs, and find that three host galaxies have an excess in radio SFRs by a factor of >2, suggesting the existence of dust-obscured star formation, which cannot be traced by optical studies. Two of the three host galaxies, which are located in the galaxy main sequence based on optical SFRs, are found to be above the main sequence based on their radio SFRs. This suggests a higher fraction of starburst galaxies in SLSN hosts than estimated in previous studies. We calculate extinction from the ratio between radio SFRs and dust-uncorrected optical SFRs and find that the hosts are on the trend of increasing extinction with metallicity, which is consistent with the relation in local star-forming galaxies. We also place a constraint on a pulsar-driven SN model, which predicts quasi-steady synchrotron radio emission.

DOI： 10.3847/1538-4357/aab616

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