Faculty Profiles - TAMURA Yoichi

Papers - TAMURA Yoichi

Division display 101 - 120 of about 143 ／ All the affair displays >>

Molecular Gas Properties in the Host Galaxy of GRB 080207 Reviewed

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

The Astrophysical Journal Vol. 876 ( 2 ) page： 91 - 91 2019.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

We present the results of CO(1-0) and CO(4-3) observations of the host galaxy
of a long-duration gamma-ray burst GRB080207 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 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 Mgas = 8.7 x 10^10 Modot, which
places the host in a sequence of normal star-forming galaxies in a
Mgas-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 Mdust = 1.5 x 10^8 Modot. The spatially-resolving 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 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 Mgas-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 Reviewed

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

The Astrophysical Journal Vol. 876 ( 1 ) page： 1 2019.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

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 {n}<SUB>{ { H</SUB> } }<SUP>PDR</SUP>}={10}<SUP>5.5{--</SUP>5.75} cm<SUP>-3</SUP> and G <SUB>0</SUB> = 10<SUP>3.5-3.75</SUP> in the central 1 kpc region and {n}<SUB>{ { H</SUB> } }<SUP>PDR</SUP>}={10}<SUP>5.0{--</SUP>5.25} cm<SUP>-3</SUP> and G <SUB>0</SUB> = 10<SUP>3.25-3.5</SUP> 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 <SUB>[O III]</SUB>/L <SUB>[N II]</SUB> = 6.4 ± 2.2 indicates a near solar metallicity with Z <SUB>gas</SUB> = 0.7-1.0 Z <SUB>☉</SUB>, 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 Reviewed International journal

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 2019.5

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

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 Reviewed International journal

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 2019.5

Mapping Galaxy Clusters in the Distant Universe Reviewed International journal

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 2019.5

Environmental impacts on molecular gas in protocluster galaxies at z ̃ 2 Reviewed

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 Vol. 71 ( 2 ) page： 40 2019.4

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

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 (M<SUB>star</SUB>/M<SUB>☉</SUB>) < 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 (M<SUB>star</SUB>/M<SUB>☉</SUB>) > 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 Reviewed

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

The Astrophysical Journal Vol. 871 ( 2 ) 2019.2

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

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 Vol. 70 ( 6 ) page： 239 - 240 2018.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Cambridge University Press (CUP)

We present the survey design, data reduction, construction of images, and source catalog of the Atacama Large Millimeter/submillimeter Array (ALMA) twenty-six arcmin<SUP>2</SUP> survey of GOODS-S at one millimeter (ASAGAO). ASAGAO is a deep (1 σ depth ̃ 61 μJy beam<SUP>-1</SUP> for a 250 kλ-tapered map with a synthesized beam size of 0{^''<SUB>.</SUB>}51 × 0{^''<SUB>.</SUB>}45) and wide area (26 arcmin<SUP>2</SUP>) 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<SUP>-1</SUP> for a deep region with a 250 kλ-taper, and a synthesized beam size of 0{^''<SUB>.</SUB>}59 × 0{^''<SUB>.</SUB>}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^{+11}_{-8}% of the extragalactic background light at 1.2 mm is resolved into discrete sources at S<SUB>1.2 mm</SUB> > 135 μJy. We create infrared (IR) luminosity functions (LFs) in the redshift range of z = 1-3 from the ASAGAO sources with K<SUB>s</SUB>-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 (L<SUB>IR</SUB>/L<SUB>☉</SUB>) ≳ 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 Reviewed

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 Vol. 193 ( 5-6 ) page： 1003 - 1009 2018.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：SPRINGER/PLENUM PUBLISHERS

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. <P />...

DOI： 10.1007/s10909-018-1916-1

Development of Multi-temperature Calibrator for the TES Bolometer Camera: Deployment at ASTE Reviewed

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 Vol. 193 ( 5-6 ) page： 996 - 1002 2018.12

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：SPRINGER/PLENUM PUBLISHERS

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. <P />...

DOI： 10.1007/s10909-018-2009-x

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

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 Vol. 481 ( 1 ) page： L84 - L88 2018.11

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

Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) detected far-infrared emission lines such as the [O III] 88 μ m line from galaxies at z ̃ 7-9. We use a cosmological simulation of galaxy formation to study the physical properties of [O III] 88 μ m emitters. In a comoving volume of 50 h<SUP>-1</SUP> Mpc on a side, we locate 34 galaxies with stellar masses greater than 10^8 M_{☉} at z = 9, and more than 270 such galaxies at z = 7. We calculate the [O III] 88 μ m luminosities (L_{O III}, 88) by combining a physical model of H II regions with emission line calculations using the photoionization code CLOUDY. We show that the resulting L_{O III}, 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 L_{O III}, 88 > 10^8 L_{☉} have star formation rates higher than 3 M_{☉} yr^{-1}, and the typical metallicity is {̃ } 0.1 Z_{☉}. The galaxies are hosted by dark matter haloes with masses greater than 10^{11} M_{☉}. We propose to use the [O III] 5007 Å line, to be detected by James Webb Space Telescope, to study the properties of galaxies whose [O III] 88 μ m 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? Reviewed

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

The Astrophysical Journal Vol. 866 ( 2 ) 2018.10

Language：Japanese Publishing type：Research paper (scientific 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 ̃10<SUP>11-12</SUP> cm<SUP>-3</SUP>. 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 <SUB>☉</SUB> 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 ̃10<SUP>3</SUP> 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 Reviewed

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

2018.10

Publishing type：Research paper (scientific journal) Publisher：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 Reviewed International journal

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 2018.10

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

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 Reviewed

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 Vol. 560 ( 7720 ) page： 613 - + 2018.8

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

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 galaxy<SUP>1-3</SUP>, a region that is comparable in size to the massive, quiescent galaxies found at the peak of cosmic star-formation history<SUP>4</SUP> 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 galaxies<SUP>5</SUP>....

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 Reviewed

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 Vol. 70 ( 4 ) 2018.8

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

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<SUP>-1</SUP> with a {0^{^''<SUB>.</SUB>}5} resolution. Combining the present survey with earlier, archived observations, we map an area of 20 arcmin<SUP>2</SUP> (71 comoving Mpc<SUP>2</SUP> 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 S<SUB>1.1mm</SUB> = 0.43-5.6 mJy, equivalent to star-formation rates of ≳100-1000 M<SUB>☉</SUB> yr<SUP>-1</SUP> 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-z Dusty Star-forming Galaxies in an Exponential Disk (n ≃ 1) Reviewed

Fujimoto, Seiji, Ouchi, Masami, Kohno, Kotaro, Yamaguchi, Yuki, Hatsukade, Bunyo, Ueda, Yoshihiro, Shibuya, Takatoshi, Inoue, Shigeki, Oogi, Taira, Toft, Sune, Gómez-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.

The Astrophysical Journal Vol. 861 ( 1 ) 2018.7

Language：English Publishing type：Research paper (scientific 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 arcmin<SUP>2</SUP> area in GOODS-S. In conjunction with the ALMA archival data, our sample consists of 45 ALMA sources with infrared luminosity (L <SUB>IR</SUB>) range of ̃10<SUP>11</SUP>-10<SUP>13</SUP> L <SUB>☉</SUB>. 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 <SUB>FIR</SUB> = 1.2 ± 0.2 and R <SUB>e,FIR</SUB> = 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 <SUB>opt</SUB> and effective radius R <SUB>e,opt</SUB> with deep Hubble Space Telescope (HST) images. Interestingly, we obtain n <SUB>opt</SUB> = 0.9 ± 0.3 (≃n <SUB>FIR</SUB>) and R <SUB>e,opt</SUB> = 3.2 ± 0.6 kpc (>R <SUB>e,FIR</SUB>), 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 <SUB>opt</SUB> = 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, Koshida, Shintaro, Terao, Yasunori, Ohashi, Hirofumi, Kono, Yukihiro, Kushibiki, Kosuke, Yoshii, Yuzuru

Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series Vol. 10702 page： 107022H 2018.7

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPIE-INT SOC 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 pm 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 pm, 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 2.10 x1.18. 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 ≳ 6 studied with ALMA Reviewed

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 Vol. 70 ( 3 ) 2018.6

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

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 (M<SUB>1450</SUB> > -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)× 10<SUP>8</SUP> L_{☉} and L<SUB>FIR</SUB> = (1.2-2.0) × 10<SUP>11</SUP> 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<SUP>-1</SUP>. 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}]}/L_FIR ratios of the hosts, ≃ (2.2-8.7) × 10<SUP>-3</SUP>, 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) × 10<SUP>10</SUP> 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 Reviewed

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

The Astrophysical Journal Vol. 857 ( 1 ) page： 72 - 72 2018.4

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