Updated on 2024/04/01

写真a

 
UMEHATA Hideki
 
Organization
Institute for Advanced Research Designated assistant professor
Graduate School of Science Designated assistant professor
Title
Designated assistant professor
Contact information
メールアドレス
External link

Degree 1

  1. Doctor of Science ( 2015.3   The University of Tokyo ) 

Research Interests 10

  1. Cosmic Web

  2. Large-scale structures

  3. Astronomy of galaxies

  4. Radio Astronomy

  5. 超巨大ブラックホール

  6. 電波天文学

  7. 銀河天文学

  8. 超巨大ブラックホール

  9. 宇宙網

  10. 宇宙大規模構造

Research Areas 2

  1. Natural Science / Astronomy

  2. Natural Science / Astronomy

Current Research Project and SDGs 1

  1. Astronomy

Research History 19

  1. Nagoya University   Institute for Advanced Research   Designated assistant professor

    2022.4

  2. Nagoya University   Graduate School of Science   Designated assistant professor

    2022.4

  3. カリフォルニア工科大学   天文学専攻   訪問研究者

    2023.7

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  4. Nagoya University

    2022.4

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  5. Nagoya University

    2022.4

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  6. The University of Tokyo   Institute for Cosmic Ray Research   Researcher   ICRR fellow

    2021.10 - 2022.3

  7. The University of Tokyo   Institute for Cosmic Ray Research

    2021.10 - 2022.3

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  8. RIKEN   Cluster for Pioneering Research   Researcher   Special Postdoctoral Researcher

    2018.4 - 2022.9

  9. RIKEN

    2018.4 - 2022.9

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  10. The Open University of Japan   Researcher   Postdoctral fellow

    2016.10 - 2018.3

  11. The Open University of Japan   Faculty of Liberal Arts

    2016.10 - 2018.3

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  12. The University of Tokyo   Institute of Astronomy   Researcher

    2016.4 - 2016.9

  13. The University of Tokyo   Graduate School of Science Institute of Astronomy

    2016.4 - 2016.9

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  14. Japan Society for Promotion of Science   JSPS Research Fellowship for Young Scientists (PD)

    2015.4 - 2016.3

  15. European Southern Observatory   Researcher   Visiting Researcher

    2015.4 - 2016.3

  16. 欧州南天天文台   客員研究員

    2015.4 - 2016.3

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  17. Japan Society for the Promotion of Science

    2015.4 - 2016.3

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  18. Japan Society for Promotion of Science   JSPS Research Fellowship for Young Scientists

    2014.4 - 2015.3

  19. Japan Society for the Promotion of Science

    2014.4 - 2015.3

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Education 6

  1. The University of Tokyo   Division of Science   Department of Astronomy

    2012.4 - 2015.3

  2. The University of Tokyo   Graduate School of Science

    2012.4 - 2015.3

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  3. The University of Tokyo   Division of Science   Department of Astronomy

    2010.4 - 2012.3

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    Country: Japan

  4. The University of Tokyo   Graduate School of Science

    2010.4 - 2012.3

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  5. The University of Tokyo   Division of Science   Department of Astronomy

    2006.4 - 2010.3

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    Country: Japan

  6. The University of Tokyo   Faculty of Science   Department of Astronomy

    2006.4 - 2010.3

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Professional Memberships 2

  1. The Astronomical Society of Japan

    2010.4

  2. 日本天文学会

    2010.4

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Committee Memberships 5

  1.   JWST Cycle-3 External Reviewer  

    2023.10 - 2024.3   

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    Committee type:Other

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  2. TMT-ACCESS Organizers   Organizer  

    2023.4   

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    Committee type:Other

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  3. LSTサイエンス白書   AGN・SMBH班班長  

    2022.1   

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  4. SPICAサイエンス検討会   銀河BH進化班  

    2019.4 - 2021.3   

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  5.   ALMA Cycle-10 Large Program External Reviewer  

       

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Awards 3

  1. The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology, The Young Scientists’ Award

    2023.4   Ministry of Education, Culture, Sports, Science and Technology (MEXT)   Study of the cosmic web connecting active galaxies in the proto-cluster

    Hideki Umehata

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  2. The 11th RIKEN Ohbu Research Incentive Award

    2020.3   RIKEN   Discovery of large scale hydrogen gas filaments feeding galaxies and blackholes in a protocluster

    Hideki Umehata

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    Award type:Award from Japanese society, conference, symposium, etc. 

  3. 欧文研究報告論文賞

    2021.3   日本天文学会   Big Three Dragons: A z = 7.15 Lyman-break galaxy detected in [O III] 88μm, [C II] 158μm, and dust continuum with ALMA

    橋本拓也、井上昭雄、馬渡健、田村陽一、松尾宏、古澤久徳、播金優一、澁谷隆俊、Kirsten K. Knudsen、河野孝太郎、小野宜昭、Erik Zackrisson、岡本崇、柏川伸成、Pascal A. Oesch、大内正己、太田一陽、清水一紘、谷口義明、梅畑豪紀、Darach Watson

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Papers 114

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

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

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

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

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

    DOI: 10.1126/science.aaw5949

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  2. An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of <i>z</i>=2-5 Ultra- and Hyperluminous Infrared Galaxies

    Liao, CL; Chen, CC; Wang, WH; Smail, I; Ao, Y; Chapman, SC; Dudzeviciute, U; Castillo, MF; Lee, MM; Serjeant, S; Swinbank, AM; Taylor, DJ; Umehata, H; Zhao, Y

    ASTROPHYSICAL JOURNAL   Vol. 961 ( 2 )   2024.2

  3. J0107a: A Barred Spiral Dusty Star-forming Galaxy at z = 2.467

    Shuo Huang, Ryohei Kawabe, Kotaro Kohno, Toshiki Saito, Shoichiro Mizukoshi, Daisuke Iono, Tomonari Michiyama, Yoichi Tamura, Christopher C. Hayward, Hideki Umehata

    The Astrophysical Journal Letters   Vol. 958 ( 2 )   2023.12

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    Dusty Star-Forming Galaxies (DSFGs) are amongst the most massive and active
    star-forming galaxies during the cosmic noon. Theoretical studies have proposed
    various formation mechanisms of DSFGs, including major merger-driven starbursts
    and secular star-forming disks. Here, we report J0107a, a bright ($\sim8$ mJy
    at observed-frame 888 $\mu$m) DSFG at $z=2.467$ that appears to be a gas-rich
    massive disk and might be an extreme case of the secular disk scenario. J0107a
    has a stellar mass $M_\star\sim5\times10^{11}M_\odot$, molecular gas mass
    $M_\mathrm{mol}\sim(1\textendash6)\times10^{11}M_\odot$, and a star formation
    rate (SFR) of $\sim500M_\odot$ yr$^{-1}$. J0107a does not have a gas-rich
    companion. The rest-frame 1.28 $\mu$m JWST NIRCam image of J0107a shows a
    grand-design spiral with a prominent stellar bar extending $\sim15$ kpc. ALMA
    band 7 continuum map reveals that the dust emission originates from both the
    central starburst and the stellar bar. 3D disk modeling of the CO(4-3) emission
    line indicates a dynamically cold disk with rotation-to-dispersion ratio
    $V_\mathrm{max}/\sigma\sim8$. The results suggest a bright DSFG may have a
    non-merger origin, and its vigorous star formation may be triggered by bar
    and/or rapid gas inflow.

    DOI: 10.3847/2041-8213/acff63

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    Other Link: http://arxiv.org/pdf/2310.01782v3

  4. Probing Ultralate Reionization: Direct Measurements of the Mean Free Path over 5 &lt; <i>z</i> &lt; 6

    Zhu, YD; Becker, GD; Christenson, HM; D'Aloisio, A; Bosman, SEI; Bakx, T; D'Odorico, V; Bischetti, M; Cain, C; Davies, FB; Davies, RL; Eilers, AC; Fan, XH; Gaikwad, P; Haehnelt, MG; Keating, LC; Kulkarni, G; Lai, SM; Ma, HX; Mesinger, A; Qin, YX; Satyavolu, S; Takeuchi, TT; Umehata, H; Yang, JY

    ASTROPHYSICAL JOURNAL   Vol. 955 ( 2 )   2023.10

  5. Detection of stellar light from quasar host galaxies at redshifts above 6

    Xuheng Ding, Masafusa Onoue, John D. Silverman, Yoshiki Matsuoka, Takuma Izumi, Michael A. Strauss, Knud Jahnke, Camryn L. Phillips, Junyao Li, Marta Volonteri, Zoltan Haiman, Irham Taufik Andika, Kentaro Aoki, Shunsuke Baba, Rebekka Bieri, Sarah E.I. Bosman, Connor Bottrell, Anna Christina Eilers, Seiji Fujimoto, Melanie Habouzit, Masatoshi Imanishi, Kohei Inayoshi, Kazushi Iwasawa, Nobunari Kashikawa, Toshihiro Kawaguchi, Kotaro Kohno, Chien Hsiu Lee, Alessandro Lupi, Jianwei Lyu, Tohru Nagao, Roderik Overzier, Jan Torge Schindler, Malte Schramm, Kazuhiro Shimasaku, Yoshiki Toba, Benny Trakhtenbrot, Maxime Trebitsch, Tommaso Treu, Hideki Umehata, Bram P. Venemans, Marianne Vestergaard, Fabian Walter, Feige Wang, Jinyi Yang

    Nature   Vol. 621 ( 7977 ) page: 51 - +   2023.9

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

    The detection of starlight from the host galaxies of quasars during the reionization epoch (z > 6) has been elusive, even with deep Hubble Space Telescope observations 1,2. The current highest redshift quasar host detected 3, at z = 4.5, required the magnifying effect of a foreground lensing galaxy. Low-luminosity quasars 4–6 from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) 7 mitigate the challenge of detecting their underlying, previously undetected host galaxies. Here we report rest-frame optical images and spectroscopy of two HSC-SSP quasars at z > 6 with the JWST. Using near-infrared camera imaging at 3.6 and 1.5 μm and subtracting the light from the unresolved quasars, we find that the host galaxies are massive (stellar masses of 13 × and 3.4 × 1010 M ☉, respectively), compact and disc-like. Near-infrared spectroscopy at medium resolution shows stellar absorption lines in the more massive quasar, confirming the detection of the host. Velocity-broadened gas in the vicinity of these quasars enables measurements of their black hole masses (1.4 × 109 and 2.0 × 108 M ☉, respectively). Their location in the black hole mass–stellar mass plane is consistent with the distribution at low redshift, suggesting that the relation between black holes and their host galaxies was already in place less than a billion years after the Big Bang.

    DOI: 10.1038/s41586-023-06345-5

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  6. Characterizing CO Emitters in the SSA22-AzTEC26 Field

    Shuo Huang, Hideki Umehata, Ryohei Kawabe, Kotaro Kohno, Minju Lee, Yoichi Tamura, Bunyo Hatsukade, Ken Mawatari

    Astrophysical Journal   Vol. 953 ( 1 )   2023.8

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    We report the physical characterization of four CO emitters detected near the bright submillimeter galaxy (SMG) SSA22-AzTEC26. We analyze the data from Atacama Large Millimeter/submillimeter Array band 3, 4, and 7 observations of the SSA22-AzTEC26 field. In addition to the targeted SMG, we detect four line emitters with signal-to-noise ratio >5.2 in the cube smoothed with a 300 km s−1 FWHM Gaussian filter. All four sources have NIR counterparts within 1″. We perform UV-to-FIR spectral energy distribution modeling to derive the photometric redshifts and physical properties. Based on the photometric redshifts, we reveal that two of them are CO(2-1) at redshifts of 1.113 and 1.146 and one is CO(3-2) at z = 2.124. The three sources are massive galaxies with a stellar mass ≳1010.5 M ⊙, but have different levels of star formation. Two lie within the scatter of the main sequence (MS) of star-forming galaxies at z ∼ 1-2, and the most massive galaxy lies significantly below the MS. However, all three sources have a gas fraction within the scatter of the MS scaling relation. This shows that a blind CO line search can detect massive galaxies with low specific star formation rates that still host large gas reservoirs and that it also complements targeted surveys, suggesting later gas acquisition and the need for other mechanisms in addition to gas consumption to suppress star formation.

    DOI: 10.3847/1538-4357/ace0c0

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    Other Link: http://arxiv.org/pdf/2301.09296v3

  7. Revisiting the Properties of X-Ray Active Galactic Nuclei in the SSA22 Protocluster: Normal Supermassive Black Hole and Host-galaxy Growth for AGNs in a z = 3.09 Overdensity

    Erik B. Monson, Keith Doore, Rafael T. Eufrasio, Bret D. Lehmer, David M. Alexander, Chris M. Harrison, Mariko Kubo, Cristian Saez, Hideki Umehata

    The Astrophysical Journal   Vol. 951 ( 1 )   2023.7

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    DOI: 10.3847/1538-4357/acd449

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  8. The 300 pc Resolution Imaging of a z = 8.31 Galaxy: Turbulent Ionized Gas and Potential Stellar Feedback 600 Million Years after the Big Bang Reviewed

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

    The Astrophysical Journal   Vol. 952 ( 1 )   2023.7

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

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

    DOI: 10.3847/1538-4357/acd637

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  9. A variable active galactic nucleus at z=2.06 triply-imaged by the galaxy cluster MACS J0035.4-2015

    Furtak, LJ; Mainali, R; Zitrin, A; Plat, A; Fujimoto, S; Donahue, M; Nelson, EJ; Bauer, FE; Uematsu, R; Caminha, GB; Andrade-Santos, F; Bradley, LD; Caputi, KI; Charlot, S; Chevallard, J; Coe, D; Curtis-Lake, E; Espada, D; Frye, BL; Knudsen, KK; Koekemoer, AM; Kohno, K; Kokorev, V; Laporte, N; Lee, MM; Lemaux, BC; Magdis, GE; Sharon, K; Stark, DP; Su, YY; Suess, KA; Ueda, Y; Umehata, H; Vidal-García, A; Wu, JF

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 522 ( 4 ) page: 5142 - 5151   2023.5

  10. The SSA22 H i Tomography Survey (SSA22-HIT). I. Data Set and Compiled Redshift Catalog

    Mawatari, K; Inoue, AK; Yamada, T; Hayashino, T; Prochaska, JX; Lee, KG; Tejos, N; Kashikawa, N; Otsuka, T; Yamanaka, S; Schlegel, DJ; Matsuda, Y; Hennawi, JF; Iwata, I; Umehata, H; Mukae, S; Ouchi, M; Sugahara, Y; Tamura, Y

    ASTRONOMICAL JOURNAL   Vol. 165 ( 5 )   2023.5

  11. Bright extragalactic ALMA redshift survey (BEARS) III: detailed study of emission lines from 71 Herschel targets

    Hagimoto, M; Bakx, TJLC; Serjeant, S; Bendo, GJ; Urquhart, SA; Eales, S; Harrington, KC; Tamura, Y; Umehata, H; Berta, S; Cooray, AR; Cox, P; De Zotti, G; Lehnert, MD; Riechers, DA; Scott, D; Temi, P; van der Werf, PP; Yang, C; Amvrosiadis, A; Andreani, PM; Baker, AJ; Beelen, A; Borsato, E; Buat, V; Butler, KM; Dannerbauer, H; Dunne, L; Dye, S; Enia, AFM; Fan, L; Gavazzi, R; González-Nuevo, J; Harris, AI; Herrera, CN; Hughes, DH; Ismail, D; Ivison, RJ; Jones, B; Kohno, K; Krips, M; Lagache, G; Marchetti, L; Massardi, M; Messias, H; Negrello, M; Neri, R; Omont, A; Perez-Fournon, I; Sedgwick, C; Smith, MWL; Stanley, F; Verma, A; Vlahakis, C; Ward, B; Weiner, C; Weiss, A; Young, AJ

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 521 ( 4 ) page: 5508 - 5535   2023.3

  12. Updated Measurements of [O iii] 88 μm, [C ii] 158 μm, and Dust Continuum Emission from a z = 7.2 Galaxy Reviewed

    Yi W. Ren, Yoshinobu Fudamoto, Akio K. Inoue, Yuma Sugahara, Tsuyoshi Tokuoka, Yoichi Tamura, Hiroshi Matsuo, Kotaro Kohno, Hideki Umehata, Takuya Hashimoto, Rychard J. Bouwens, Renske Smit, Nobunari Kashikawa, Takashi Okamoto, Takatoshi Shibuya, Ikkoh Shimizu

    The Astrophysical Journal   Vol. 945 ( 1 ) page: 69   2023.3

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    DOI: 10.3847/1538-4357/acb8ab

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  13. ALMA Lensing Cluster Survey: Properties of Millimeter Galaxies Hosting X-Ray-detected Active Galactic Nuclei

    Ryosuke Uematsu, Yoshihiro Ueda, Kotaro Kohno, Satoshi Yamada, Yoshiki Toba, Seiji Fujimoto, Bunyo Hatsukade, Hideki Umehata, Daniel Espada, Fengwu Sun, Georgios E. Magdis, Vasily Kokorev, Yiping Ao

    The Astrophysical Journal   Vol. 945 ( 2 )   2023.3

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    We report the multi-wavelength properties of millimeter galaxies hosting
    X-ray detected active galactic nuclei (AGNs) from the ALMA Lensing Cluster
    Survey (ALCS). ALCS is an extensive survey of well-studied lensing clusters
    with ALMA, covering an area of 133 arcmin$^2$ over 33 clusters with a 1.2 mm
    flux-density limit of ${\sim}$60 $\mathrm{\mu Jy}$ ($1\sigma$). Utilizing the
    archival data of Chandra, we identify three AGNs at $z=$1.06, 2.09, and 2.84
    among the 180 millimeter sources securely detected in the ALCS (of which 155
    are inside the coverage of Chandra). The X-ray spectral analysis shows that two
    AGNs are not significantly absorbed ($\log N_{\mathrm{H } }/\mathrm{cm}^{-2} <
    23$), while the other shows signs of moderate absorption ($\log
    N_{\mathrm{H } }/\mathrm{cm}^{-2}\sim 23.5$). We also perform spectral energy
    distribution (SED) modelling of X-ray to millimeter photometry. We find that
    our X-ray AGN sample shows both high mass accretion rates (intrinsic 0.5--8 keV
    X-ray luminosities of ${\sim}10^{\text{44--45 } }\,\mathrm{erg\ s^{-1 } }$) and
    star-formation rates (${\gtrsim}100\,M_{\odot}\,\mathrm{yr}^{-1}$). This
    demonstrates that a wide-area survey with ALMA and Chandra can selectively
    detect intense growth of both galaxies and supermassive black holes (SMBHs) in
    the high-redshift universe.

    DOI: 10.3847/1538-4357/acb4e9

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    Other Link: http://arxiv.org/pdf/2301.09275v1

  14. Massive Molecular Gas Companions Uncovered by Very Large Array CO(1-0) Observations of the z=5.2 Radio Galaxy TN J0924-2201 Reviewed

    Kianhong Lee, Kotaro Kohno, Bunyo Hatsukade, Fumi Egusa, Takuji Yamashita, Malte Schramm, Kohei Ichikawa, Masatoshi Imanishi, Takuma Izumi, Tohru Nagao, Yoshiki Toba, Hideki Umehata

    ASTROPHYSICAL JOURNAL   Vol. 944 ( 1 )   2023.2

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

    We present Karl G. Jansky Very Large Array K-band (19 GHz) observations of the redshifted CO(1-0) line emission toward the radio galaxy TN J0924-2201 at z = 5.2, which is one of the most distant radio galaxies with CO detected. With an angular resolution of similar to 2 '', the CO(1-0) line emission is resolved into three clumps, within +/- 500 km s(-1) relative to its redshift, which is determined by Ly alpha. We find that the clumps are located off-center and 12-33 kpc away from the center of the host galaxy, which has counterparts in the Hubble Space Telescope i band, Spitzer/IRAC, and the Atacama Large Millimeter/submillimeter Array (ALMA) band 6 (230 GHz; 1.3 mm). With the ALMA detection, we estimate the infrared luminosity LIR and the star formation rate (SFR) of the host galaxy to be (9.3 +/- 1.7) x 10(11)L(circle dot) and 110 +/- 20 M-circle dot yr(-1), respectively. We also derive the 3 sigma upper limit of M-H2 < 1.3 x 10(10) M-circle dot at the host galaxy. The 2 detected CO(1-0) line luminosities of the three clumps, L '(CO (1-0)) = (3.2-4.7) x 10(10) K km s(-1) pc(2), indicate the presence of three massive molecular gas reservoirs, with M-H2 = (2.5-3.7) x 10(10) M-circle dot, assuming a CO-to-H-2 conversion factor of alpha(CO) = 0.8 M-circle dot (K km s(-1) pc(2))(-1), although the SFR is not elevated due to the nondetection of the ALMA -1.3 mm continuum (SFR < 40 M-circle dot yr(-1)). From the host galaxy, the nearest molecular gas clump, labeled "clump A," is apparently in alignment with the radio jet axis, showing radio-CO alignment. The origins of these three clumps around TN J0924-2201 can possibly be interpreted as outflows, mergers, or jet-induced metal enrichment.

    DOI: 10.3847/1538-4357/acaf58

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  15. Central concentration of warm and dense molecular gas in a strongly lensed submillimeter galaxy at z = 6 Reviewed

    Akiyoshi Tsujita, Ken-ichi Tadaki, Kotaro Kohno, Bunyo Hatsukade, Fumi Egusa, Yoichi Tamura, Yuri Nishimura, Jorge Zavala, Toshiki Saito, Hideki Umehata, Minju M Lee

    Publications of the Astronomical Society of Japan   Vol. 74 ( 6 ) page: 1429 - 1440   2022.12

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    DOI: 10.1093/pasj/psac082

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  16. ALMA Lensing Cluster Survey: Hubble Space Telescope and Spitzer Photometry of 33 Lensed Fields Built with CHArGE Reviewed

    V. Kokorev, G. Brammer, S. Fujimoto, K. Kohno, G. E. Magdis, F. Valentino, S. Toft, P. Oesch, I. Davidzon, F. E. Bauer, D. Coe, E. Egami, M. Oguri, M. Ouchi, M. Postman, J. Richard, J. B. Jolly, K. K. Knudsen, F. Sun, J. R. Weaver, Y. Ao, A. J. Baker, L. Bradley, K. I. Caputi, M. Dessauges-Zavadsky, D. Espada, B. Hatsukade, A. M. Koekemoer, A. M. Muñoz Arancibia, K. Shimasaku, H. Umehata, T. Wang, W. H. Wang

    Astrophysical Journal, Supplement Series   Vol. 263 ( 2 )   2022.12

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    We present a set of multiwavelength mosaics and photometric catalogs in the Atacama Large Millimeter/ submillimeter Array (ALMA) lensing cluster survey fields. The catalogs were built by the reprocessing of archival data from the Complete Hubble Archive for Galaxy Evolution compilation, taken by the Hubble Space Telescope (HST) in the Reionization Lensing Cluster Survey, Cluster Lensing And Supernova survey with Hubble, and Hubble Frontier Fields. Additionally, we have reconstructed the Spitzer Infrared Array Camera 3.6 and 4.5 μm mosaics, by utilizing all the available archival IPAC Infrared Science Archive/Spitzer Heritage Archive exposures. To alleviate the effect of blending in such a crowded region, we have modeled the Spitzer photometry by convolving the HST detection image with the Spitzer point-spread function using the novel GOLFIR software. The final catalogs contain 218,000 sources, covering a combined area of 690 arcmin2, a factor of ∼2 improvement over the currently existing photometry. A large number of detected sources is a result of reprocessing of all available and sometimes deeper exposures, in conjunction with a combined optical–near-IR detection strategy. These data will serve as an important tool in aiding the search of the submillimeter galaxies in future ALMA surveys, as well as follow-ups of the HST dark and high-z sources with JWST. Coupled with the available HST photometry, the addition of the 3.6 and 4.5 μm bands will allow us to place a better constraint on the photometric redshifts and stellar masses of these objects, thus giving us an opportunity to identify high-redshift candidates for spectroscopic follow-ups and to answer the important questions regarding the Epoch of Reionization and formation of the first galaxies. The mosaics, photometric catalogs, and the best-fit physical properties are publicly available at https:// github.com/dawn-cph/alcs-clusters.

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  17. An AGN with an Ionized Gas Outflow in a Massive Quiescent Galaxy in a Protocluster at z = 3.09 Reviewed

    Mariko Kubo, Hideki Umehata, Yuichi Matsuda, Masaru Kajisawa, Charles C. Steidel, Toru Yamada, Ichi Tanaka, Bunyo Hatsukade, Yoichi Tamura, Kouichiro Nakanishi, Kotaro Kohno, Kianhong Lee, Keiichi Matsuda, Yiping Ao, Tohru Nagao, Min S. Yun

    The Astrophysical Journal   Vol. 935 ( 2 ) page: 89 - 89   2022.8

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    We report the detection of an ionized gas outflow from an X-ray active galactic nucleus hosted in a massive quiescent galaxy in a protocluster at z = 3.09 (J221737.29+001823.4). It is a type-2 QSO with broad (W<sub>80</sub> &gt; 1000 km s<sup>−1</sup>) and strong ($\mathrm{log}({L}_{[\mathrm{OIII}]}$/erg s<sup>−1</sup>) ≈ 43.4) [O iii]λλ 4959,5007 emission lines detected by slit spectroscopy in three-position angles using Multi-Object Infra-Red Camera and Spectrograph (MOIRCS) on the Subaru telescope and the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) on the Keck-I telescope. In the all slit directions, [O iii] emission is extended to ∼15 physical kpc and indicates a powerful outflow spreading over the host galaxy. The inferred ionized gas mass outflow rate is 22 ± 3 M<sub>⊙</sub> yr<sup>−1</sup>. Although it is a radio source, according to the line diagnostics using Hβ, [O ii], and [O iii], photoionization by the central QSO is likely the dominant ionization mechanism rather than shocks caused by radio jets. On the other hand, the spectral energy distribution of the host galaxy is well characterized as a quiescent galaxy that has shut down star formation several hundred Myr ago. Our results suggest a scenario that QSOs are powered after the shutdown of the star formation and help complete the quenching of massive quiescent galaxies at high redshift.

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  18. Detection of nitrogen and oxygen in a galaxy at the end of reionization Reviewed

    Ken-ichi Tadaki, Akiyoshi Tsujita, Yoichi Tamura, Kotaro Kohno, Bunyo Hatsukade, Daisuke Iono, Minju M Lee, Yuichi Matsuda, Tomonari Michiyama, Tohru Nagao, Kouichiro Nakanishi, Yuri Nishimura, Toshiki Saito, Hideki Umehata, Jorge Zavala

    Publications of the Astronomical Society of Japan   Vol. 74 ( 3 ) page: L9 - L16   2022.6

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    We present observations of [N ii] 205 μm, [O iii] 88 μm, and dust emission in a strongly-lensed, submillimeter galaxy (SMG) at z = 6.0, G09.83808, with the Atacama Large Millimeter/submillimeter Array (ALMA). Both [N ii] and [O iii] line emissions are detected at &amp;gt;12σ in the ${0{^{\prime \prime}_{. } }8}$-resolution maps. Lens modeling indicates that the spatial distribution of the dust continuum emission is well characterized by a compact disk with an effective radius of 0.64 ± 0.02 kpc and a high infrared surface brightness of ΣIR = (1.8 ± 0.3) × 1012 L⊙ kpc−2. This result supports that G09.83808 is the progenitor of compact quiescent galaxies at z ∼ 4, where the majority of its stars are expected to be formed through a strong and short burst of star formation. G09.83808 and other lensed SMGs show a decreasing trend in the [N ii] line to infrared luminosity ratio with increasing continuum flux density ratio between 63 and 158 μm, as seen in local luminous infrared galaxies (LIRGs). The decreasing trend can be reproduced by photoionization models with increasing ionization parameters. Furthermore, by combining the [N ii]/[O iii] luminosity ratio with far-infrared continuum flux density ratio in G09.83808, we infer that the gas phase metallicity is already Z ≈ 0.5–0.7 Z⊙. G09.83808 is likely one of the earliest galaxies that has been chemically enriched at the end of reionization.

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  19. An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Survey Description and First Results Reviewed

    Chen, CC; Liao, CL; Smail, I; Swinbank, AM; Ao, Y; Bunker, AJ; Chapman, SC; Hatsukade, B; Ivison, RJ; Lee, MM; Serjeant, S; Umehata, H; Wang, WH; Zhao, Y

    ASTROPHYSICAL JOURNAL   Vol. 929 ( 2 )   2022.4

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    We introduce an ALMA band 3 spectroscopic survey targeting the brightest submillimeter galaxies (SMGs) in the COSMOS field. Here we present the first results based on the 18 primary SMGs that have 870 μm flux densities of S 870 = 12.4-19.3 mJy and are drawn from a parent sample of 260 ALMA-detected SMGs from the AS2COSMOS survey. We detect emission lines in 17 and determine their redshifts to be in the range of z = 2-5 with a median of 3.3 ± 0.3. We confirm that SMGs with brighter S 870 are located at higher redshifts. The data additionally cover five fainter companion SMGs, and we obtain line detection in one. Together with previous studies, our results indicate that for SMGs that satisfy our selection, their brightest companion SMGs are physically associated with their corresponding primary SMGs ≥40% of the time, suggesting that mergers play a role in the triggering of star formation. By modeling the foreground gravitational fields, <10% of the primary SMGs can be strongly lensed with a magnification μ > 2. We determine that about 90% of the primary SMGs have lines that are better described by double Gaussian profiles, and the median separation of the two Gaussian peaks is 430 ± 40 km s-1. This allows estimates of an average baryon mass, which, together with the line dispersion measurements, puts our primary SMGs on the similar mass-σ correlation found on local early-type galaxies. Finally, the number density of our z > 4 primary SMGs is found to be 1-0.6+0.9×10-6 cMpc-3, suggesting that they can be the progenitors of z ∼3-4 massive quiescent galaxies.

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  20. FOREVER22: galaxy formation in protocluster regions

    Hidenobu Yajima, Makito Abe, Sadegh Khochfar, Kentaro Nagamine, Akio K Inoue, Tadayuki Kodama, Shohei Arata, Claudio Dalla Vecchia, Hajime Fukushima, Takuya Hashimoto, Nobunari Kashikawa, Mariko Kubo, Yuexing Li, Yuichi Matsuda, Ken Mawatari, Masami Ouchi, Hideki Umehata

    Monthly Notices of the Royal Astronomical Society   Vol. 509 ( 3 ) page: 4037 - +   2022.1

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    <title>ABSTRACT</title>
    We present results from a new cosmological hydrodynamics simulation campaign of protocluster (PC) regions, FOREVER22: FORmation and EVolution of galaxies in Extremely overdense Regions motivated by SSA22. The simulations cover a wide range of cosmological scales using three different zoom set-ups in a parent volume of $(714.2~\rm cMpc)^{3}$: PCR (Proto-Cluster Region; V = (28.6 cMpc)3, SPH particle mass, mSPH = 4.1 × 106 M⊙, and final redshift, zend = 2.0), BCG (Brightest proto-Cluster Galaxy; V ∼ (10 cMpc)3, mSPH = 5.0 × 105 M⊙ and zend = 4.0), and First (V ∼ (3 cMpc)3, mSPH = 7.9 × 103 M⊙ and zend = 9.5) runs, that allow us to focus on different aspects of galaxy formation. In the PCR runs, we follow 10 PCs, each harbouring 1–4 SMBHs with ${\rm M_{\rm BH } }\ge 10^{9}~{\rm M_{\odot } }$. One of the PC cores shows a spatially close arrangement of seven starburst galaxies with ${\rm SFR} \gtrsim 100~{\rm {\rm M_{\odot } }~{\rm yr^{-1 } } }$ each, that are dust-obscured and would appear as submillimetre galaxies with flux ≳1 mJy at $1.1~ \rm mm$ in observations. The BCG runs show that the total SFRs of haloes hosting BCGs are affected by AGN feedback, but exceed $1000~{\rm {\rm M_{\odot } }~{\rm yr^{-1 } } }$ at z ≲ 6. The First runs resolve mini-haloes hosting population (Pop) III stars and we show that, in PC regions, the dominant stellar population changes from Pop III to Pop II at z ≳ 20, and the first galaxies with ${\rm SFR} \gtrsim 18~{\rm {\rm M_{\odot } }~{\rm yr^{-1 } } }$ form at z ∼ 10. These can be prime targets for future observations with the James Webb Space Telescope. Our simulations successfully reproduce the global star formation activities in observed PCs and suggest that PCs can kickstart cosmic reionization.

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  21. On the Nature of AGN and Star Formation Enhancement in the <i>z</i>=3.1 SSA22 Protocluster: The HST WFC3 IR View

    Monson, EB; Lehmer, BD; Doore, K; Eufrasio, RT; Bonine, B; Alexander, DM; Harrison, CM; Kubo, M; Mantha, KB; Saez, C; Straughn, A; Umehata, H

    ASTROPHYSICAL JOURNAL   Vol. 919 ( 1 )   2021.9

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    We examine possible environmental sources of the enhanced star formation and active galactic nucleus (AGN) activity in the z = 3.09 SSA22 protocluster using Hubble WFC3 F160W (~1.6 µm) observations of the SSA22 field, including new observations centered on eight X-ray selected protocluster AGN. To investigate the role of mergers in the observed AGN and star formation enhancement, we apply both quantitative (Sérsic-fit and Gini-M20) and visual morphological classifications to F160W images of protocluster Lyman-break galaxies (LBGs) in the fields of the X-ray AGN and z ~ 3 field LBGs in SSA22 and GOODS-N. We find no statistically significant differences between the morphologies and merger fractions of protocluster and field LBGs, though we are limited by small number statistics in the protocluster. We also fit the UV-to-near-IR spectral energy distributions of F160W-detected protocluster and field LBGs to characterize their stellar masses and star formation histories. We find that the mean protocluster LBG is a factor of ~2 times more massive and more attenuated than the mean z ~ 3 field LBG. We take our results to suggest that ongoing mergers are not more common among protocluster LBGs than field LBGs, though protocluster LBGs appear to be more massive. We speculate that the larger mass of the protocluster LBGs contributes to the enhancement of SMBH mass and accretion rate in the protocluster, which in turn drives the observed protocluster AGN enhancement.

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  22. ALMA observations of Lyα blob 1: Multiple major mergers and widely distributed interstellar media

    Hideki Umehata, Ian Smail, Charles C. Steidel, Matthew Hayes, Douglas Scott, A. M. Swinbank, R. J. Ivison, Toru Nagao, Mariko Kubo, Kouichiro Nakanishi, Yuichi Matsuda, Soh Ikarashi, Yoichi Tamura, J. E. Geach

    Astrophysical Journal   Vol. 918 ( 2 )   2021.9

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    We present observations of a giant Lyα blob (LAB) in the SSA22 protocluster at z = 3.1, SSA22-LAB1, taken with the Atacama Large Millimeter/submillimeter Array. Dust continuum, along with [C II] 158 μm and CO(4–3) line emission have been detected in LAB1, showing complex morphology and kinematics across a ∼100 kpc central region. Seven galaxies at z = 3.0987–3.1016 in the surroundings are identified in [C II] and dust continuum emission, with two of them potential companions or tidal structures associated with the most massive galaxies. Spatially resolved [C II] and infrared luminosity ratios for the widely distributed media (L[CII]/LIR ≈ 10-2-10-3) suggest that the observed extended interstellar media are likely to have originated from star formation activity and the contribution from shocked gas is probably not dominant. LAB1 is found to harbor a total molecular gas mass Mmol = (8.7 ± 2.0) × 1010 Me, concentrated in the core region of the Lyα-emitting area. While (primarily obscured) star formation activity in the LAB1 core is one of the most plausible power sources for the Lyα emission, multiple major mergers found in the core may also play a role in making LAB1 exceptionally bright and extended in Lyα as a result of cooling radiation induced by gravitational interactions.

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  23. A massive quiescent galaxy confirmed in a protocluster at z=3.09

    Mariko Kubo, Hideki Umehata, Yuichi Matsuda, Masaru Kajisawa, Charles C. Steidel, Toru Yamada, Ichi Tanaka, Bunyo Hatsukade, Yoichi Tamura, Kouichiro Nakanishi, Kotaro Kohno, Kianhong Lee, Keiichi Matsuda

    Astrophysical Journal   Vol. 919 ( 1 )   2021.9

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    We report a massive quiescent galaxy at zspec= -3.0922+0.008-0.004 spectroscopically confirmed at a protocluster in the SSA22 field by detecting the Balmer and Ca II absorption features with the multi-object spectrometer for infrared exploration on the Keck I telescope. This is the most distant quiescent galaxy confirmed in a protocluster to date. We fit the optical to mid-infrared photometry and spectrum simultaneously with spectral energy distribution (SED) models of parametric and nonparametric star formation histories (SFHs). Both models fit the observed SED well and confirm that this object is a massive quiescent galaxy with a stellar mass of log (M∗/M⊙=11.26+0.03-0.04 and 11.54+0.03-0.00 and a star formation rate of SFR/M⊙ yr-1 < 0.3 and = -0.01+0.03-0.01 for parametric and nonparametric models, respectively. The SFH from the former modeling is described as an instantaneous starburst whereas that of the latter modeling is longer-lived, but both models agree with a sudden quenching of the star formation at ~0.6 Gyr ago. This massive quiescent galaxy is confirmed in an extremely dense group of galaxies predicted as a progenitor of a brightest cluster galaxy formed via multiple mergers in cosmological numerical simulations. We discover three new plausible [O III]λ5007 emitters at 3.0791 ≤ zspec ≤ 3.0833 serendipitously detected around the target. Two of them just between the target and its nearest massive galaxy are possible evidence of their interactions. They suggest the future great size and stellar mass evolution of this massive quiescent galaxy via mergers.

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  24. Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XIII. Large-scale Feedback and Star Formation in a Low-luminosity Quasar at z = 7.07 on the Local Black Hole to Host Mass Relation

    Takuma Izumi, Yoshiki Matsuoka, Seiji Fujimoto, Masafusa Onoue, Michael A. Strauss, Hideki Umehata, Masatoshi Imanishi, Kotaro Kohno, Toshihiro Kawaguchi, Taiki Kawamuro, Shunsuke Baba, Tohru Nagao, Yoshiki Toba, Kohei Inayoshi, John D. Silverman, Akio K. Inoue, Soh Ikarashi, Kazushi Iwasawa, Nobunari Kashikawa, Takuya Hashimoto, Kouichiro Nakanishi, Yoshihiro Ueda, Malte Schramm, Chien-Hsiu Lee, Hyewon Suh

    The Astrophysical Journal   Vol. 914 ( 1 ) page: 36 - 36   2021.6

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  25. Dense and Warm Neutral Gas in BR 1202-0725 at z = 4.7 as Traced by the [O I] 145 μm Line

    Minju M. Lee, Tohru Nagao, Carlos De Breuck, Stefano Carniani, Giovanni Cresci, Bunyo Hatsukade, Ryohei Kawabe, Kotaro Kohno, Roberto Maiolino, Fillipo Mannucci, Alessandro Marconi, Kouichiro Nakanishi, Paulina Troncoso, Hideki Umehata

    The Astrophysical Journal   Vol. 913 ( 1 ) page: 41 - 41   2021.5

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  26. ALMA Lensing Cluster Survey: Bright [C ii] 158 mu m Lines from a Multiply Imaged Sub-L* Galaxy at z=6.0719

    Seiji Fujimoto, Masamune Oguri, Gabriel Brammer, Yuki Yoshimura, Nicolas Laporte, Jorge Gonzalez-Lopez, Gabriel B. Caminha, Kotaro Kohno, Adi Zitrin, Johan Richard, Masami Ouchi, Franz E. Bauer, Ian Smail, Bunyo Hatsukade, Yoshiaki Ono, Vasily Kokorev, Hideki Umehata, Daniel Schaerer, Kirsten Knudsen, Fengwu Sun, Georgios Magdis, Francesco Valentino, Yiping Ao, Sune Toft, Miroslava Dessauges-Zavadsky, Kazuhiro Shimasaku, Karina Caputi, Haruka Kusakabe, Kana Morokuma-Matsui, Kikuchihara Shotaro, Eiichi Egami, Minju M. Lee, Timothy Rawle, Daniel Espada

    ASTROPHYSICAL JOURNAL   Vol. 911 ( 2 )   2021.4

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    We present bright [C ii] 158 mu m line detections from a strongly magnified and multiply imaged (mu similar to 20-160) sub-L* (MUV=-19.75-0.44+0.55) Lyman-break galaxy (LBG) at z = 6.0719 +/- 0.0004, drawn from the ALMA Lensing Cluster Survey (ALCS). Emission lines are identified at 268.7 GHz at >= 8 sigma exactly at the positions of two multiple images of the LBG, behind the massive galaxy cluster RXCJ0600-2007. Our lens models, updated with the latest spectroscopy from VLT/MUSE, indicate that a sub region of the LBG crosses the caustic, and is lensed into a long (similar to 6 '') arc with a local magnification of mu similar to 160, for which the [C ii] line is also significantly detected. The source plane reconstruction resolves the interstellar medium (ISM) structure, showing that the [C ii] line is co-spatial with the rest-frame UV continuum at a scale of similar to 300 pc. The [C ii] line properties suggest that the LBG is a rotation-dominated system, whose velocity gradient explains a slight difference in redshifts between the whole LBG and its sub-region. The star formation rate (SFR)-L-[CII] relations, for whole and sub-regions of the LBG, are consistent with those of local galaxies. We evaluate the lower limit of the faint-end of the [C ii] luminosity function at z = 6, finding it to be consistent with predictions from semi-analytical models and from the local SFR-L-[CII] relation with a SFR function at z = 6. These results imply that the local SFR-L-[CII] relation is universal for a wide range of scales, including the spatially resolved ISM, the whole region of the galaxy, and the cosmic scale, even in the epoch of reionization.

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  27. A puzzling non-detection of [O III] and [C II] from a z ≈ 7.7 galaxy observed with ALMA

    C. Binggeli, A. K. Inoue, T. Hashimoto, M. C. Toribio, E. Zackrisson, S. Ramstedt, K. Mawatari, Y. Harikane, H. Matsuo, T. Okamoto, K. Ota, I. Shimizu, Y. Tamura, Y. Taniguchi, H. Umehata

    Astronomy & Astrophysics   Vol. 646   page: A26 - A26   2021.2

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    <italic>Context.</italic> Characterizing the galaxy population in the early Universe holds the key to understanding the evolution of these objects and the role they played in cosmic reionization. However, there have been very few observations at the very highest redshifts to date.


    <italic>Aims.</italic> In order to shed light on the properties of galaxies in the high-redshift Universe and their interstellar media, we observe the Lyman-<italic>α</italic> emitting galaxy <ext-link ext-link-type="aoi">z7_GSD_3811</ext-link> at <italic>z</italic> = 7.664 with bands 6 and 8 at the Atacama Large Millimeter/submillimeter Array (ALMA).


    <italic>Methods.</italic> We target the far-infrared [O <sc>III</sc>] 88 <italic>μ</italic>m and [C <sc>II</sc>] 158 <italic>μ</italic>m emission lines and dust continuum in the star-forming galaxy z7_GSD_3811 with ALMA. We combine these measurements with earlier observations in the rest-frame ultraviolet (UV) in order to characterize the object and compare the results to those of earlier studies that observed [O <sc>III</sc>] and [C <sc>II</sc>] emission in high-redshift galaxies.


    <italic>Results.</italic> The [O <sc>III</sc>] 88 <italic>μ</italic>m and [C <sc>II</sc>] 158 <italic>μ</italic>m emission lines are undetected at the position of z7_GSD_3811, with 3<italic>σ</italic> upper limits of 1.6  ×  10<sup>8</sup> <italic>L</italic><sub>⊙</sub> and 4.0  ×  10<sup>7</sup> <italic>L</italic><sub>⊙</sub>, respectively. We do not detect any dust continuum in band 6 nor band 8. The measured rms in the band 8 and band 6 continua are 26 and 9.9 <italic>μ</italic>Jy beam<sup>−1</sup>, respectively. Similar to several other high-redshift galaxies, z7_GSD_3811 exhibits low [C <sc>II</sc>] emission for its star formation rate compared to local galaxies. Furthermore, our upper limit on the [O <sc>III</sc>] line luminosity is lower than the previously observed [O <sc>III</sc>] lines in high-redshift galaxies with similar UV luminosities. Our ALMA band 6 and 8 dust continuum observations imply that z7_GSD_3811 likely has a low dust content, and our non-detections of the [O <sc>III</sc>] and [C <sc>II</sc>] lines could indicate that z7_GSD_3811 has a low metallicity (<italic>Z</italic> ≲ 0.1 <italic>Z</italic><sub>⊙</sub>).

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  28. Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XII. Extended [C ii] Structure (Merger or Outflow) in a z = 6.72 Red Quasar

    Takuma Izumi, Masafusa Onoue, Yoshiki Matsuoka, Michael A. Strauss, Seiji Fujimoto, Hideki Umehata, Masatoshi Imanishi, Taiki Kawamuro, Tohru Nagao, Yoshiki Toba, Kotaro Kohno, Nobunari Kashikawa, Kohei Inayoshi, Toshihiro Kawaguchi, Kazushi Iwasawa, Akio K. Inoue, Tomotsugu Goto, Shunsuke Baba, Malte Schramm, Hyewon Suh, Yuichi Harikane, Yoshihiro Ueda, John D. Silverman, Takuya Hashimoto, Yasuhiro Hashimoto, Soh Ikarashi, Daisuke Iono, Chien-Hsiu Lee, Kianhong Lee, Takeo Minezaki, Kouichiro Nakanishi, Suzuka Nakano, Yoichi Tamura, Ji-Jia Tang

    The Astrophysical Journal   Vol. 908 ( 2 ) page: 235 - 235   2021.2

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    We present Atacama Large Millimeter/submillimeter Array [C ii] 158 μm line and far-infrared (FIR) continuum emission observations toward HSC J120505.09−000027.9 (J1205−0000) at z = 6.72 with a beam size of ∼0.″8 × 0.″5 (or 4.1 kpc × 2.6 kpc), the most distant red quasar known to date. Red quasars are modestly reddened by dust and are thought to be in rapid transition from an obscured starburst to an unobscured normal quasar, driven by powerful active galactic nucleus (AGN) feedback that blows out a cocoon of interstellar medium. The FIR continuum of J1205−0000 is bright, with an estimated luminosity of L<sub>FIR</sub> ∼ 3 × 10<sup>12</sup>L<sub>⊙</sub>. The [C ii] line emission is extended on scales of r ∼ 5 kpc, greater than that of the FIR continuum. The line profiles at the extended regions are complex and broad (FWHM ∼ 630–780 km s<sup>−1</sup>). Although it is not practical to identify the nature of this extended structure, possible explanations include (i) companion/merging galaxies and (ii) massive AGN-driven outflows. For the case of (i), the companions are modestly star-forming (∼10 M<sub>⊙</sub> yr<sup>−1</sup>) but are not detected by our Subaru optical observations (y<sub>AB,5σ</sub> = 24.4 mag). For the case of (ii), our lower limit to the cold neutral outflow rate is ∼100 M<sub>⊙</sub> yr<sup>−1</sup>. The outflow kinetic energy and momentum are both much lower than predicted in energy-conserving wind models, suggesting that the AGN feedback in this quasar is not capable of completely suppressing its star formation.

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  29. FIR-luminous [C ii] Emitters in the ALMA-SCUBA-2 COSMOS Survey (AS2COSMOS): The Nature of Submillimeter Galaxies in a 10 Comoving Megaparsec-scale Structure at z ∼ 4.6

    I. Mitsuhashi, Y. Matsuda, Ian Smail, N. H. Hayatsu, J. M. Simpson, A. M. Swinbank, H. Umehata, U. Dudzevičiūtė, J. E. Birkin, S. Ikarashi, Chian-Chou Chen, K. Tadaki, H. Yajima, Y. Harikane, H. Inami, S. C. Chapman, B. Hatsukade, D. Iono, A. Bunker, Y. Ao, T. Saito, J. Ueda, S. Sakamoto

    The Astrophysical Journal   Vol. 907 ( 2 ) page: 122 - 122   2021.2

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  30. ALMA Lensing Cluster Survey: An ALMA Galaxy Signposting a MUSE Galaxy Group at z = 4.3 Behind “El Gordo”

    K. I. Caputi, G. B. Caminha, S. Fujimoto, K. Kohno, F. Sun, E. Egami, S. Deshmukh, F. Tang, Y. Ao, L. Bradley, D. Coe, D. Espada, C. Grillo, B. Hatsukade, K. K. Knudsen, M. M. Lee, G. E. Magdis, K. Morokuma-Matsui, P. Oesch, M. Ouchi, P. Rosati, H. Umehata, F. Valentino, E. Vanzella, W.-H. Wang, J. F. Wu, A. Zitrin

    The Astrophysical Journal   Vol. 908 ( 2 ) page: 146 - 146   2021.2

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  31. A puzzling non-detection of [O III] and [C II] from a z ≈ 7.7 galaxy observed with ALMA

    Binggeli C., Inoue A. K., HASHIMOTO Takuya, Toribio M. C., Zackrisson E., Ramstedt S., Mawatari K., Harikane Y., Matsuo H., Okamoto T., Ota K., Shimizu I., Tamura Y., Taniguchi Y., Umehata H.

    Astronomy & Astrophysics   Vol. 646   page: A26   2021.2

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  32. ALMA Deep Field in SSA22

    Hideki Umehata, Ian Smail, A. M. Swinbank, Kotaro Kohno, Yoichi Tamura, Tao Wang, Yiping Ao, Bunyo Hatsukade, Mariko Kubo, Kouchiro Nakanishi, Natsuki N. Hayatsu

    Astronomy & Astrophysics   Vol. 640   page: L8 - L8   2020.8

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    Deep surveys with the Atacama Large Millimeter Array (ALMA) have uncovered a population of dusty star-forming galaxies which are faint or even undetected at optical to near-infrared wavelengths. Their faintness at short wavelengths makes the detailed characterization of the population challenging. Here we present a spectroscopic redshift identification and a characterization of one of these near-infrared-dark galaxies discovered by an ALMA deep survey. The detection of [C <sc>I</sc>](1–0) and CO(4–3) emission lines determines the precise redshift of the galaxy, ADF22.A2, to be <italic>z</italic> = 3.9913 ± 0.0008. On the basis of a multi-wavelength analysis, ADF22.A2 is found to be a massive, star-forming galaxy with a stellar mass of <italic>M</italic><sub>∗</sub> = 1.1<sub>−0.6</sub><sup>+1.3</sup> × 10<sup>11</sup> <italic>M</italic><sub>⊙</sub> and SFR = 430<sub>−150</sub><sup>+230</sup> <italic>M</italic><sub>⊙</sub> yr<sup>−1</sup>. The molecular gas mass was derived to be <italic>M</italic>(H<sub>2</sub>)<sup>[CI]</sup> = (5.9 ± 1.5)×10<sup>10</sup> <italic>M</italic><sub>⊙</sub>, indicating a gas fraction of ≈35%, and the ratios of <italic>L</italic><sub>[CI](1−0)</sub>/<italic>L</italic><sub>IR</sub> and <italic>L</italic><sub>[CI](1−0)</sub>/<italic>L</italic><sub>CO(4−3)</sub> suggest that the nature of the interstellar medium in ADF22.A2 is in accordance with those of other bright submillimeter galaxies. The properties of ADF22.A2, including the redshift, star-formation rate, stellar mass, and depletion time scale (<italic>τ</italic><sub>dep</sub> ≈ 0.1−0.2 Gyr), also suggest that ADF22.A2 has the characteristics expected for the progenitors of quiescent galaxies at <italic>z</italic> ≳ 3. Our results demonstrate the power of ALMA contiguous mapping and line scan, which help us to obtain an unbiased view of galaxy formation in the early Universe.

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  33. ALMA twenty-six arcmin2 survey of GOODS-S at one millimeter (ASAGAO): Millimeter properties of stellar mass selected galaxies

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

    Publications of the Astronomical Society of Japan   Vol. 72 ( 4 )   2020.8

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    We make use of the ALMA twenty-Six Arcmin2 survey of GOODS-S At One-millimeter (ASAGAO), deep 1.2 mm continuum observations of a 26-arcmin2 region in the Great Observatories Origins Deep Survey-South (GOODS-S) obtained with Atacama Large Millimeter/sub-millimeter Array (ALMA), to probe dust-enshrouded star formation in K-band selected (i.e., stellar mass selected) galaxies, which are drawn from the FourStar Galaxy Evolution Survey (ZFOURGE) catalog. Based on the ASAGAO combined map, which was created by combining ASAGAO and ALMA archival data in the GOODS-South field, we find that 24 ZFOURGE sources have 1.2 mm counterparts with a signal-to-noise ratio &amp;gt;4.5 (1σ ≃ 30–70 μJy beam−1 at 1.2 mm). Their median redshift is estimated to be $z$median = 2.38 ± 0.14. They generally follow the tight relationship of the stellar mass versus star formation rate (i.e., the main sequence of star-forming galaxies). ALMA-detected ZFOURGE sources exhibit systematically larger infrared (IR) excess (IRX ≡ LIR/LUV) compared to ZFOURGE galaxies without ALMA detections even though they have similar redshifts, stellar masses, and star formation rates. This implies the consensus stellar-mass versus IRX relation, which is known to be tight among rest-frame-ultraviolet-selected galaxies, cannot fully predict the ALMA detectability of stellar-mass-selected galaxies. We find that ALMA-detected ZFOURGE sources are the main contributors to the cosmic IR star formation rate density at $z$ = 2–3.

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  34. An ALMA survey of the brightest sub-millimetre sources in the SCUBA-2–COSMOS field

    J M Simpson, Ian Smail, U Dudzevičiūtė, Y Matsuda, B-C Hsieh, W-H Wang, A M Swinbank, S M Stach, Fang Xia An, J E Birkin, Y Ao, A J Bunker, S C Chapman, Chian-Chou Chen, K E K Coppin, S Ikarashi, R J Ivison, I Mitsuhashi, T Saito, H Umehata, R Wang, Y Zhao

    Monthly Notices of the Royal Astronomical Society   Vol. 495 ( 3 ) page: 3409 - 3430   2020.7

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    ABSTRACT

    We present an ALMA study of the ∼180 brightest sources in the SCUBA-2 850-μm map of the COSMOS field from the S2COSMOS survey, as a pilot study for AS2COSMOS – a full survey of the ∼1000 sources in this field. In this pilot study, we have obtained 870-μm continuum maps of an essentially complete sample of the brightest 182 sub-millimetre sources ($S_{850\, \mu \rm m}\gt $ 6.2 mJy) in COSMOS. Our ALMA maps detect 260 sub-millimetre galaxies (SMGs) spanning a range in flux density of $S_{870\, \mu \rm m}$ = 0.7–19.2 mJy. We detect more than one SMG counterpart in 34 ± 2 per cent of sub-millimetre sources, increasing to 53 ± 8 per cent for SCUBA-2 sources brighter than $S_{850\, \mu \rm m}\gt $ 12 mJy. We estimate that approximately one-third of these SMG–SMG pairs are physically associated (with a higher rate for the brighter secondary SMGs, $S_{870\, \mu \rm m}\gtrsim$ 3 mJy), and illustrate this with the serendipitous detection of bright [C ii] 157.74-μm line emission in two SMGs, AS2COS 0001.1 and 0001.2 at z = 4.63, associated with the highest significance single-dish source. Using our source catalogue, we construct the interferometric 870-μm number counts at $S_{870\, \mu \rm m}\gt $ 6.2 mJy. We use the extensive archival data of this field to construct the multiwavelength spectral energy distribution of each AS2COSMOS SMG, and subsequently model this emission with magphys to estimate their photometric redshifts. We find a median photometric redshift for the $S_{870\, \mu \rm m}\gt $ 6.2 mJy AS2COSMOS sample of z = 2.87 ± 0.08, and clear evidence for an increase in the median redshift with 870-μm flux density suggesting strong evolution in the bright end of the 870-μm luminosity function.

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  35. ALMA uncovers the [C ii] emission and warm dust continuum in a z = 8.31 Lyman break galaxy

    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   Vol. 493 ( 3 ) page: 4294 - 4307   2020.4

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    We report on the detection of the [C ii] 157.7 μm emission from the Lyman break galaxy (LBG) MACS0416_Y1 at z = 8.3113, by using the Atacama Large Millimeter/submillimeter Array (ALMA). The luminosity ratio of [O iii] 88 μm (from previous campaigns) to [C ii] is 9.3 ± 2.6, indicative of hard interstellar radiation fields and/or a low covering fraction of photodissociation regions. The emission of [C ii] is cospatial to the 850 μm dust emission (90 μm rest frame, from previous campaigns), however the peak [C ii] emission does not agree with the peak [O iii] emission, suggesting that the lines originate from different conditions in the interstellar medium. We fail to detect continuum emission at 1.5 mm (160 μm rest frame) down to 18 μJy (3σ). This non-detection places a strong limits on the dust spectrum, considering the 137 ± 26 μJy continuum emission at 850 μm. This suggests an unusually warm dust component (T > 80 K, 90 per cent confidence limit), and/or a steep dust-emissivity index (βdust > 2), compared to galaxy-wide dust emission found at lower redshifts (typically T ∼ 30–50 K, βdust ∼ 1–2). If such temperatures are common, this would reduce the required dust mass and relax the dust production problem at the highest redshifts. We therefore warn against the use of only single-wavelength information to derive physical properties, recommend a more thorough examination of dust temperatures in the early Universe, and stress the need for instrumentation that probes the peak of warm dust in the Epoch of Reionization.

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  36. ALMA band 8 observations of DLA 2233+131 at z = 3.150 Reviewed

    Ogura, Kazuyuki, Umehata, Hideki, Taniguchi, Yoshiaki, Matsuda, Yuichi, Kashikawa, Nobunari, Sheth, Kartik, Murata, Katsuhiro, Kajisawa, Masaru, Kobayashi, Masakazu A. R., Murayama, Takashi, Nagao, Tohru

    Publications of the Astronomical Society of Japan   Vol. 72 ( 2 ) page: id.29 - 11   2020.4

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    <jats:title>Abstract</jats:title>
    <jats:p>We present our ALMA Band 8 observations of a damped Ly$\alpha$ absorption (DLA) system at $z = 3.150$ observed in the spectrum of the quasar Q2233+131 at $z = 3.295$. The optical counterpart of this DLA has been identified and it shows a double-peaked Ly$\alpha$ emission line. Since one possible origin of DLAs at high redshift is an outflowing gas from star-forming galaxies, DLA 2233+131 provides a good laboratory to investigate the nature of high-z DLAs. Motivated by this, we have carried out ALMA band 8 observations to study the [C ii] line in this system. However, we do not detect any significant emission line in the observed pass bands. Instead, we have serendipitously found three submm continuum sources in the observed sky area. One appears to be the quasar Q2233+131 itself while the other two sources are newly identified submm galaxies (SMGs), called SMG1 and SMG2 in this paper. They are located at a separation of ${4{^{\prime \prime }_{. } }7}$ and ${8{^{\prime \prime }_{. } }1}$ from Q2233+131, respectively. Their 646 μm fluxes are $6.35\:$mJy and $6.43\:$mJy, respectively, being higher than that of Q2233+131, $3.62\:$mJy. Since these two SMGs are not detected in the optical images obtained with the Hubble Space Telescope and the Subaru Telescope, they have a very red spectral energy distribution. It is, therefore, suggested that they are high-redshift galaxies or very dusty galaxies at intermediate redshift, although we cannot rule out the possibility that they are optically very faint SMG analogs at low redshift. Follow-up observations will be necessary to explore the nature of this interesting region.</jats:p>

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  37. A Noncorotating Gas Component in an Extreme Starburst at z = 4.3

    Ken-ichi Tadaki, Daisuke Iono, Min S. Yun, Itziar Aretxaga, Bunyo Hatsukade, Minju M. Lee, Tomonari Michiyama, Kouichiro Nakanishi, Toshiki Saito, Junko Ueda, Hideki Umehata

    The Astrophysical Journal   Vol. 889 ( 2 ) page: 141 - 141   2020.2

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    We report the detection of a non-corotating gas component in a bright
    unlensed submillimeter galaxy at z=4.3, COSMOS-AzTEC-1, hosting a compact
    starburst. ALMA 0.17 and 0.09 arcsec resolution observations of [CII] emission
    clearly demonstrate that the gas kinematics is characterized by an ordered
    rotation. After subtracting the best-fit model of a rotating disk, we
    kinematically identify two residual components in the channel maps. Both
    observing simulations and analysis of dirty images confirm that these two
    subcomponents are not artificially created by noise fluctuations and beam
    deconvolution. One of the two has a velocity offset of 200 km/s and a physical
    separation of 2 kpc from the primary disk and is located along the kinematic
    minor axis of disk rotation. We conclude that this gas component is falling
    into the galaxy from a direction perpendicular to the disk rotation. The
    accretion of such small non-corotating gas components could stimulate violent
    disk instability, driving radial gas inflows into the center of galaxies and
    leading to formation of in-situ clumps such as identified in dust continuum and
    CO. We require more theoretical studies on high gas fraction mergers with mass
    ratio of 1:>10 to verify this process.

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  38. ALMA uncovers the [CII] emission and warm dust continuum in a z = 8.31 Lyman break galaxy Reviewed

    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

        2020.1

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    We report on the detection of the [CII] 157.7 $\mu$m emission from the Lyman break galaxy (LBG) MACS0416_Y1 at z = 8.3113, by using the Atacama Large Millimeter/submillimeter Array (ALMA). The luminosity ratio of [OIII] 88 $\mu$m (from previous campaigns) to [CII] is 9.31 $\pm$ 2.6, indicative of hard interstellar radiation fields and/or a low covering fraction of photo-dissociation regions. The emission of [CII] is cospatial to the 850 $\mu$m dust emission (90 $\mu$m rest-frame, from previous campaigns), however the peak [CII] emission does not agree with the peak [OIII] emission, suggesting that the lines originate from different conditions in the interstellar medium. We fail to detect continuum emission at 1.5 mm (160 $\mu$m rest-frame) down to 18 $\mu$Jy (3$\sigma$). This nondetection places a strong limit on the dust spectrum, considering the 137 $\pm$ 26 $\mu$Jy continuum emission at 850 $\mu$m. This suggests an unusually warm dust component (T $&gt;$ 80 K, 90% confidence limit), and/or a steep dust-emissivity index ($\beta_{\rm dust}$ $&gt;$ 2), compared to galaxy-wide dust emission found at lower redshifts (typically T $\sim$ 30 - 50 K, $\beta_{\rm dust}$ $\sim$ 1 - 2). If such temperatures are common, this would reduce the required dust mass and relax the dust production problem at the highest redshifts. We therefore warn against the use of only single-wavelength information to derive physical properties, recommend a more thorough examination of dust temperatures in the early Universe, and stress the need for instrumentation that probes the peak of warm dust in the Epoch of Reionization....

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

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

    Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X   Vol. 11453   2020

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

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

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

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

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  41. 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 Reviewed

    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   Vol. 71 ( 6 )   2019.12

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    We present ALMA [C II] line and far-infrared (FIR) continuum observations of three z &gt; 6 low-luminosity quasars (M_1450 &gt; -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) × 10^8 L_{☉}, about one order of magnitude smaller than optically luminous (M_1450 ≲ -25 mag) quasars. The FIR continuum luminosities range from &lt; 9 × 10^{10} L_{☉} (3 σ limit) to {̃ } 2 × 10^{12} 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 (M_dyn) as a surrogate for bulge stellar mass (M_{ bulge}), we find that a significant fraction of low-luminosity quasars are located on or even below the local M_{ BH}-M_{ bulge} 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 M_{ BH}-M_{ bulge} 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....

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  42. Detections of far-infrared [OIII] and dust emission in a galaxy at z = 8.312: Early metal enrichment in the heart of the reionization era

    Y. Tamura, K. Mawatari, T. Hashimoto, A. K. Inoue, E. Zackrissonm, L. Christensen, C. Binggeli, Y. Matsuda, H. Matsuo, T. T. Takeuchi, R. S. Asano, K. Sunaga, I. Shimizu, T. Okamoto, N. Yoshida, M. Lee, T. Shibuya, Y. Taniguchi, H. Umehata, B. Hatsukade, K. Kohno, K. Ota

    Proceedings of the International Astronomical Union   Vol. 15 ( S341 ) page: 211 - 215   2019.11

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    <title>Abstract</title>We present ALMA detection of the [O <sc>iii</sc>] 88 <italic>μ</italic>m line and 850 <italic>μ</italic>m dust continuum emission in a <italic>Y</italic>-dropout Lyman break galaxy, MACS0416_Y1. The [O <sc>iii</sc>] detection confirms the object with a spectroscopic redshift to be <italic>z</italic> = 8.3118±0.0003. The 850 <italic>μ</italic>m continuum intensity (0.14 mJy) implies a large dust mass on the order of 4×10<sup>6</sup><italic>M</italic><sub>⊙</sub>. The ultraviolet-to-far infrared spectral energy distribution modeling, where the [O <sc>iii</sc>] emissivity model is incorporated, suggests the presence of a young (τ<sub>age</sub> ≍ 4 Myr), star-forming (SFR ≍ 60<italic>M</italic><sub>⊙</sub>yr<sup>−1</sup>), and moderately metal-polluted (<italic>Z</italic> ≍ 0.2<italic>Z</italic><sub>⊙</sub>) stellar component with a stellar mass of 3 × 10<sup>8</sup><italic>M</italic><sub>⊙</sub>. An analytic dust mass evolution model with a single episode of star formation does not reproduce the metallicity and dust mass in ≍ 4 Myr, suggesting an underlying evolved stellar component as the origin of the dust mass.

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  43. SILVERRUSH. VIII. Spectroscopic Identications of Early Large Scale Structures with Protoclusters Over 200 Mpc at z=6-7: Strong Associations of Dusty Star-Forming Galaxies Reviewed

    Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Seiji Fujimoto, Darko Donevski, Takatoshi Shibuya, Andreas L. Faisst, Tomotsugu Goto, Bunyo Hatsukade, Nobunari Kashikawa, Kotaro Kohno, Takuya Hashimoto, Ryo Higuchi, Akio K. Inoue, Yen-Ting Lin, Crystal L. Martin, Roderik Overzier, Ian Smail, Jun Toshikawa, Hideki Umehata, Yiping Ao, Scott Chapman, David L. Clements, Myungshin Im, Yipeng Jing, Toshihiro Kawaguchi, Chien-Hsiu Lee, Minju M. Lee, Lihwai Lin, Yoshiki Matsuoka, Murilo Marinello, Tohru Nagao, Masato Onodera, Sune Toft, Wei-Hao Wang

    The Astrophysical Journal   Vol. 883 ( 2 ) page: 142 - 142   2019.10

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  44. First [N II]122 μm Line Detection in a QSO-SMG Pair BRI 1202-0725 at z = 4.69 Reviewed

    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

    The Astrophysical Journal   Vol. 883 ( 2 )   2019.10

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    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 {26}<SUB>-11</SUB><SUP>+12</SUP> and {134}<SUB>-39</SUB><SUP>+50</SUP> cm<SUP>-3</SUP> 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 &gt; 4 for probing the interstellar medium conditions and the effects on surrounding environments....

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

    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

    The Astrophysical Journal   Vol. 883 ( 1 )   2019.9

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    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 <SUB>cl</SUB>/M <SUB>☉</SUB>) = 13.4-13.6, suggesting that the protocluster would evolve into a Virgo-like cluster (&gt;10<SUP>14</SUP> M <SUB>☉</SUB>). We compare the CO line widths and the CO luminosities with other (proto)clusters (n <SUB>gal</SUB> = 91) and general field (n <SUB>gal</SUB> = 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....

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  46. "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $μ$m, [CII] 158 $μ$m, and Dust Continuum with ALMA Reviewed

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

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   Vol. 71 ( 4 )   2019.8

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    We present new ALMA observations and physical properties of a Lyman Break
    Galaxy at z=7.15. Our target, B14-65666, has a bright ultra-violet (UV)
    absolute magnitude, $M_{\rm UV}\approx-22.4$, and has been spectroscopically
    identified in Ly$\alpha$ with a small rest-frame equivalent width of $\approx4$
    \AA. Previous HST image has shown that the target is comprised of two spatially
    separated clumps in the rest-frame UV. With ALMA, we have newly detected
    spatially resolved [OIII] 88 $\mu$m, [CII] 158 $\mu$m, and their underlying
    dust continuum emission. In the whole system of B14-65666, the [OIII] and [CII]
    lines have consistent redshifts of $7.1520\pm0.0003$, and the [OIII]
    luminosity, $(34.4\pm4.1)\times10^{8}L_{\rm \odot}$, is about three times
    higher than the [CII] luminosity, $(11.0\pm1.4)\times10^{8}L_{\rm \odot}$. With
    our two continuum flux densities, the dust temperature is constrained to be
    $T_{\rm d}\approx50-60$ K under the assumption of the dust emissivity index of
    $\beta_{\rm d}=2.0-1.5$, leading to a large total infrared luminosity of
    $L_{\rm TIR}\approx1\times10^{12}L_{\rm \odot}$. Owing to our high spatial
    resolution data, we show that the [OIII] and [CII] emission can be spatially
    decomposed into two clumps associated with the two rest-frame UV clumps whose
    spectra are kinematically separated by $\approx200$ km s$^{-1}$. We also find
    these two clumps have comparable UV, infrared, [OIII], and [CII] luminosities.
    Based on these results, we argue that B14-65666 is a starburst galaxy induced
    by a major-merger. The merger interpretation is also supported by the large
    specific star-formation rate (defined as the star-formation rate per unit
    stellar mass), sSFR$=260^{+119}_{-57}$ Gyr$^{-1}$, inferred from our SED
    fitting. Probably, a strong UV radiation field caused by intense star formation
    contributes to its high dust temperature and the [OIII]-to-[CII] luminosity
    ratio.

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  47. ADF22: Blind Detections of [C II] Line Emitters Shown to be Spurious Reviewed

    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     2019.7

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    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.

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  48. ALMA 26 arcmin<SUP>2</SUP> Survey of GOODS-S at 1 mm (ASAGAO): Near-infrared-dark Faint ALMA Sources Reviewed

    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.

    The Astrophysical Journal   Vol. 878 ( 1 )   2019.6

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    We report detections of two 1.2 mm continuum sources (S <SUB>1.2 mm</SUB> ̃ 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 arcmin<SUP>2</SUP>) 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<SUP>-3</SUP> M <SUB>☉</SUB> yr<SUP>-1</SUP> Mpc<SUP>-3</SUP> 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 <SUB>870 μm</SUB> &gt; 4.2 mJy) at z ̃ 3-5. We also uncover three more candidate near-infrared-dark faint ALMA sources without any counterparts (S <SUB>1.2 mm</SUB> ̃ 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....

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  49. Rapid evolution and transformation into quiescence?: ALMA view on z > 6 low-luminosity quasars

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

    Proceedings of the International Astronomical Union   Vol. 15 ( S352 ) page: 139 - 143   2019.6

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    <title>Abstract</title>We present ALMA [CII] line and far-infrared (FIR) continuum observations of seven <italic>z</italic> &gt; 6 low-luminosity quasars (<italic>M</italic><sub>1450</sub> &gt; −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) × 10<sup>8</sup> L<sub>⊙</sub>, about one order of magnitude smaller than optically luminous quasars. Also found was a wide scatter of FIR continuum luminosity, ranging from <italic>L</italic><sub>FIR</sub> &lt; 10<sup>11</sup><italic>L</italic><sub>⊙</sub> to ∼2 × 10<sup>12</sup><italic>L</italic><sub>⊙</sub>. 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.

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  50. ALMA Deep Field in the SSA22 proto-cluster at z = 3

    Hideki Umehata

    Proceedings of the International Astronomical Union     page: 157 - 161   2019.6

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  51. 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 )   2019.5

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    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....

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  52. Exploration and characterization of the earliest epoch of galaxy formation: beyond the re-ionization era Reviewed

    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

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    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 />...

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  53. 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 )   2019.4

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    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 &lt; log (M<SUB>star</SUB>/M<SUB>☉</SUB>) &lt; 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>) &gt; 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....

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  54. Detection of the Far-infrared [O III] and Dust Emission in a Galaxy at Redshift 8.312: Early Metal Enrichment in the Heart of the Reionization Era Reviewed

    Yoichi Tamura, Ken Mawatari, Takuya Hashimoto, Akio K. Inoue, Erik Zackrisson, Lise Christensen, Christian Binggeli, Yuichi Matsuda, Hiroshi Matsuo, Tsutomu T. Takeuchi, Ryosuke S. Asano, Kaho Sunaga, Ikkoh Shimizu, Takashi Okamoto, Naoki Yoshida, Minju Lee, Takatoshi Shibuya, Yoshiaki Taniguchi, Hideki Umehata, Bunyo Hatsukade, Kotaro Kohno, Kazuaki Ota

    ASTROPHYSICAL JOURNAL   Vol. 874 ( 1 ) page: 27   2019.3

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    We present the Atacama Large Millimeter/submillimeter Array (ALMA) detection
    of the [O III] 88 $\mu$m line and rest-frame 90 $\mu$m dust continuum emission
    in a Y-dropout Lyman break galaxy (LBG), MACS0416_Y1, lying behind the Frontier
    Field cluster MACS J0416.1-2403. This [O III] detection confirms the LBG with a
    spectroscopic redshift of $z = 8.3118 \pm 0.0003$, making this object one of
    the furthest galaxies ever identified spectroscopically. The observed 850
    $\mu$m flux density of $137 \pm 26$ $\mu$Jy corresponds to a de-lensed total
    infrared (IR) luminosity of $L_{\rm IR} = (1.7 \pm 0.3) \times 10^{11}
    L_{\odot}$ if assuming a dust temperature of $T_{\rm dust} = 50$ K and an
    emissivity index of $\beta = 1.5$, yielding a large dust mass of $4 \times 10^6
    M_{\odot}$. The ultraviolet-to-far IR spectral energy distribution modeling
    where the [O III] emissivity model is incorporated suggests the presence of a
    young ($\tau_{\rm age} \approx 4$ Myr), star-forming (SFR $\approx 60
    M_{\odot}$ yr$^{-1}$), moderately metal-polluted ($Z \approx 0.2 Z_{\odot}$)
    stellar component with a mass of $M_{\rm star} = 3 \times 10^8 M_{\odot}$. An
    analytic dust mass evolution model with a single episode of star-formation does
    not reproduce the metallicity and dust mass in $\tau_{\rm age} \approx 4$ Myr,
    suggesting a pre-existing evolved stellar component with $M_{\rm star} \sim 3
    \times 10^9 M_{\odot}$ and $\tau_{\rm age} \sim 0.3$ Gyr as the origin of the
    dust mass.

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  55. 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

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  56. 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 )   2018.12

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    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> &gt; 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 &lt; z &lt; 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....

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  57. A high dust emissivity index β for a CO-faint galaxy in a filamentary Lyα nebula at z=3.1

    Kato, Y; Matsuda, Y; Iono, D; Hatsukade, B; Umehata, H; Kohno, K; Alexander, DM; Ao, YP; Chapman, SC; Hayes, M; Kubo, M; Lehmer, BD; Malkan, MA; Michiyama, T; Nagao, T; Saito, T; Tanaka, I; Taniguchi, Y

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   Vol. 70 ( 5 )   2018.10

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    We present CO J = 4-3 line and 3 mm dust continuum observations of a 100 kpc-scale filamentary Lyα nebula (SSA22 LAB18) at z = 3.1 using the Atacama Large Millimeter/submillimeter Array (ALMA). We detected the CO J = 4-3 line at a systemic zCO = 3.093 ± 0.001 at 11 σ from one of the ALMA continuum sources associated with the Lyα filament. We estimated the CO J = 4-3 luminosity of L'CO(4−3) = (2.3 ± 0.2) × 109 K km s−1 pc2 for this CO source, which is one order of magnitude smaller than those of typical z > 1 dusty star-forming galaxies (DSFGs) of similar far-infrared luminosity LIR ∼ 1012 L☉. We derived a molecular gas mass of Mgas = (4.4+−0096) × 109 M☉ and a star-formation rate of SFR =270 ± 160 M☉ yr−1. We also estimated a gas depletion time of τdep = 17 ± 10 Myr, which is shorter than those of typical DSFGs. It is suggested that this source is in the transition phase from DSFG to a gas-poor, early-type galaxy. From ALMA to Herschel multi-band dust continuum observations, we measured a dust emissivity index β = 2.3 ± 0.2, which is similar to those of local gas-poor, early-type galaxies. From recent laboratory experiments, the specific chemical compositions needed to reproduce such a high β for interstellar dust at the submillimeter wavelengths. ALMA CO and multi-band dust continuum observations can constrain the evolutionary stage of high-redshift galaxies through τdep and β, and thus we can investigate the chemical composition of dust even in the early Universe.

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  58. A gravitationally unstable gas disk of a starburst galaxy 12 billion years ago

    Ken-ichi Tadaki, Daisuke Iono, Min S. Yun, Itziar Aretxaga, Bunyo Hatsukade, David H. Hughes, So Ikarashi, Takuma Izumi, Ryohei Kawabe, Kotaro Kohno, Minju Lee, Yuichi Matsuda, Kohichiro Nakanishi, Toshiki Saito, Yoichi Tamura, Junko Ueda, Hideki Umehata, Grant W. Wilson, Tomonari Michiyama, Misaki Ando, Patrick Kamieneski

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

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    Submillimeter bright galaxies in the early Universe are vigorously forming
    stars at ~1000 times higher rate than the Milky Way. A large fraction of stars
    is formed in the central 1 kiloparsec region, that is comparable in size to
    massive, quiescent galaxies found at the peak of the cosmic star formation
    history, and eventually the core of giant elliptical galaxies in the
    present-day Universe. However, the physical and kinematic properties inside a
    compact starburst core are poorly understood because dissecting it requires
    angular resolution even higher than the Hubble Space Telescope can offer. Here
    we report 550 parsec-resolution observations of gas and dust in the brightest
    unlensed submillimeter galaxy at z=4.3. We map out for the first time the
    spatial and kinematic structure of molecular gas inside the heavily
    dust-obscured core. The gas distribution is clumpy while the underlying disk is
    rotation-supported. Exploiting the high-quality map of molecular gas mass
    surface density, we find a strong evidence that the starburst disk is
    gravitationally unstable, implying that the self-gravity of gas overcomes the
    differential rotation and the internal pressure by stellar radiation feedback.
    The observed molecular gas would be consumed by star formation in a timescale
    of 100 million years, that is comparable to those in merging starburst
    galaxies. Our results suggest that the most extreme starburst in the early
    Universe originates from efficient star formation due to a gravitational
    instability in the central 2 kpc region.

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  59. 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

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    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) &gt;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....

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  60. ALMA 26 Arcmin$^{2}$ Survey of GOODS-S at One-millimeter (ASAGAO): Average Morphology of High-$z$ Dusty Star-Forming Galaxies is an Exponential-Disk ($n \simeq 1$)

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

    Astrophysical Journal   Vol. 861 ( 1 )   2018.7

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    We present morphological properties of dusty star-forming galaxies at z=1-3
    determined with high-resolution (FWHM~0"19) Atacama Large
    Milllimeter/submilimeter Array (ALMA) 1-mm band maps of our ASAGAO survey
    covering a 26-arcmin^2 area in GOODS-S. In conjunction with the ALMA archival
    data, the present sample consists of 42 ALMA sources with a wide rest-frame
    far-infrared (FIR) luminosity L_FIR range of ~10^11-10^13 Lo. To obtain an
    average rest-frame 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 the dusty star-forming galaxies have the average
    FIR-wavelength Sersic 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 at the
    center, indicative of the existence of AGN. The average FIR profile agrees with
    a morphology of an exponential-disk clearly distinguished from a spheroidal
    profile (Sersic index of 4). We also examine the rest-frame optical Sersic
    index n_opt and effective radius R_e,opt with the 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 FIR-emitting disk is
    embedded within a larger stellar disk. The rest-frame UV and FIR data of HST
    and ALMA provide us a radial surface density profile of the total
    star-formation rate (SFR), where the FIR SFR dominates over the UV SFR at the
    center. Under the simple assumption of a constant SFR, a compact stellar
    distribution found in z~1-2 compact quiescent galaxies (cQGs) is well
    reproduced, while a spheroidal stellar morphology of cQGs (n_opt=4) cannot,
    suggestive of other important mechanisms such as dynamical dissipation.

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  61. Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) III. Star formation properties of the host galaxies at $z \gtrsim 6$ studied with ALMA

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

    Publications of the Astronomical Society of Japan   Vol. 70 ( 3 )   2018.6

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    We present our ALMA Cycle 4 measurements of the [CII] emission line and the
    underlying far-infrared (FIR) continuum emission from four optically
    low-luminosity ($M_{\rm 1450} > -25$) quasars at $z \gtrsim 6$ discovered by
    the Subaru Hyper Suprime Cam (HSC) survey. The [CII] line and FIR continuum
    luminosities lie in the ranges $L_{\rm [CII]} = (3.8-10.2) \times 10^8~L_\odot$
    and $L_{\rm FIR} = (1.2-2.0) \times 10^{11}~L_\odot$, which are at least one
    order of magnitude smaller than those of optically-luminous quasars at $z
    \gtrsim 6$. We estimate the star formation rates (SFR) of our targets as
    $\simeq 23-40~M_\odot ~{\rm yr}^{-1}$. 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 $L_{\rm [CII]}/L_{\rm FIR}$ ratios of the hosts, $\simeq
    (2.2-8.7) \times 10^{-3}$, are fully consistent with local star-forming
    galaxies. Using the [CII] dynamics, we derived their dynamical masses within a
    radius of 1.5-2.5 kpc as $\simeq (1.4-8.2) \times 10^{10}~M_\odot$. 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 $z \sim 6$, 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 the most of 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.

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

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

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

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    A fundamental quest of modern astronomy is to locate the earliest galaxies
    and study how they influenced the intergalactic medium a few hundred million
    years after the Big Bang. The abundance of star-forming galaxies is known to
    decline from redshifts of about 6 to 10, but a key question is the extent of
    star formation at even earlier times, corresponding to the period when the
    first galaxies might have emerged. Here we present spectroscopic observations
    of MACS1149-JD1, a gravitationally lensed galaxy observed when the Universe was
    less than four per cent of its present age. We detect an emission line of
    doubly ionized oxygen at a redshift of $9.1096\pm0.0006$, with an uncertainty
    of one standard deviation. This precisely determined redshift indicates that
    the red rest-frame optical colour arises from a dominant stellar component that
    formed about 250 million years after the Big Bang, corresponding to a redshift
    of about 15. Our results indicate the it may be possible to detect such early
    episodes of star formation in similar galaxies with future telescopes.

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  63. ALMA 26 arcmin<SUP>2</SUP> Survey of GOODS-S at One-millimeter (ASAGAO): X-Ray AGN Properties of Millimeter-selected Galaxies

    Ueda, Y., Hatsukade, B., Kohno, K., Yamaguchi, Y., Tamura, Y., Umehata, H., Akiyama, M., Ao, Y., Aretxaga, I., Caputi, K., Dunlop, J. S., Espada, D., Fujimoto, S., Hayatsu, N. H., Imanishi, M., Inoue, A. K., Ivison, R. J., Kodama, T., Lee, M. M., Matsuoka, K., Miyaji, T., Morokuma-Matsui, K., Nagao, T., Nakanishi, K., Nyland, K., Ohta, K., Ouchi, M., Rujopakarn, W., Saito, T., Tadaki, K., Tanaka, I., Taniguchi, Y., Wang, T., Wang, W. -H., Yoshimura, Y., Yun, M. S.

    The Astrophysical Journal   Vol. 853 ( 1 )   2018.1

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    We investigate the X-ray active galactic nucleus (AGN) properties of millimeter galaxies in the Great Observatories Origins Deep Survey South (GOODS-S) field detected with the Atacama Large Millimeter/submillimeter Array (ALMA), by utilizing the Chandra 7-Ms data, the deepest X-ray survey to date. Our millimeter galaxy sample comes from the ASAGAO survey covering 26 arcmin<SUP>2</SUP> (12 sources at a 1.2 mm flux-density limit of ≈ 0.6 mJy), supplemented by the deeper but narrower 1.3 mm survey of a part of the ASAGAO field by Dunlop et al. Ofthe 25 total millimeter galaxies, 14 have Chandra counterparts. The observed AGN fractions at z=1.5{--}3 are found to be {90}<SUB>-19</SUB><SUP>+8</SUP>% and {57}<SUB>-25</SUB><SUP>+23</SUP>% for the ultra-luminous and luminous infrared galaxies with log {L}<SUB>{IR</SUB>}/{L}<SUB>☉ </SUB> = 12-12.8 and log {L}<SUB>{IR</SUB>}/{L}<SUB>☉ </SUB> = 11.5-12, respectively. The majority (̃2/3) of the ALMA and/or Herschel detected X-ray AGNs at z = 1.5-3 appear to be star-formation-dominant populations, having {L}<SUB>{ { X</SUB> } }/ {L}<SUB>{IR</SUB>} ratios smaller than the “simultaneous evolution” value expected from the local black-hole-mass-to-stellar-mass ({M}<SUB>{BH</SUB>}-M <SUB>*</SUB>) relation. On the basis of the {L}<SUB>{ { X</SUB> } } and stellar mass relation, we infer that a large fraction of star-forming galaxies at z=1.5{--}3 have black hole masses that are smaller than those expected from the local {M}<SUB>{BH</SUB>}-M <SUB>*</SUB> relation. This contrasts previous reports on luminous AGNs at the same redshifts detected in wider and shallower surveys, which are subject to selection biases against lower luminosity AGNs. Our results are consistent with an evolutionary scenario in which star formation occurs first, and an AGN-dominant phase follows later, in objects that finally evolve into galaxies with classical bulges....

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  64. VizieR Online Data Catalog: mm-wave size study of ALMA submm galaxies (Ikarashi+, 2017) Reviewed

    Ikarashi} S, Caputi} K.~I, Ohta} K, Ivison} R.~J, Lagos} C.~D.~P, Bisigello} L, Hatsukade} B, Aretxaga} I, Dunlop} J.~S, Hughes} D.~H, Iono} D, Izumi} T, Kashikawa} N, Koyama} Y, Kawabe} R, Kohno} K, Motohara} K, Nakanishi} K, Tamura} Y, Umehata} H, Wilson} G.~W, Yabe} K, Yun} M

    VizieR Online Data Catalog     page: J/ApJ/849/L36   2018

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  65. A high dust emissivity index beta for a CO-faint galaxy in a filamentary Ly_alpha nebula at z = 3.1 Reviewed

    Yuta Kato, Yuichi Matsuda, Daisuke Iono, Bunyo Hatsukade, Hideki Umehata, Kotaro Kohno, David M. Alexander, Yiping Ao, Scott C. Chapman, Matthew Hayes, Mariko Kubo, Bret D. Lehmer, Matthew A. Malkan, Tomonari Michiyama, Tohru Nagao, Tomoki Saito, Ichi Tanaka, Yoshiaki Taniguch

    Publications of the Astronomical Society of Japan   Vol. 70   page: L6   2018

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  66. Deep Submillimeter and Radio Observations in the SSA22 Field. I. Powering Sources and the Lyα Escape Fraction of Lyα Blobs

    Ao, Y., Matsuda, Y., Henkel, C., Iono, D., Alexander, D. M., Chapman, S. C., Geach, J., Hatsukade, B., Hayes, M., Hine, N. K., Kato, Y., Kawabe, R., Kohno, K., Kubo, M., Lehnert, M., Malkan, M., Menten, K. M., Nagao, T., Norris, R. P., Ouchi, M., Saito, T., Tamura, Y., Taniguchi, Y., Umehata, H., Weiss, A.

    The Astrophysical Journal   Vol. 850 ( 2 )   2017.12

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    We study the heating mechanisms and Lyα escape fractions of 35 Lyα blobs (LABs) at z ≈ 3.1 in the SSA22 field. Dust continuum sources have been identified in 11 of the 35 LABs, all with star formation rates (SFRs) above 100 M <SUB>☉</SUB> yr<SUP>-1</SUP>. Likely radio counterparts are detected in 9 out of 29 investigated LABs. The detection of submillimeter dust emission is more linked to the physical size of the Lyα emission than to the Lyα luminosities of the LABs. A radio excess in the submillimeter/radio-detected LABs is common, hinting at the presence of active galactic nuclei. Most radio sources without X-ray counterparts are located at the centers of the LABs. However, all X-ray counterparts avoid the central regions. This may be explained by absorption due to exceptionally large column densities along the line-of-sight or by LAB morphologies, which are highly orientation dependent. The median Lyα escape fraction is about 3% among the submillimeter-detected LABs, which is lower than a lower limit of 11% for the submillimeter-undetected LABs. We suspect that the large difference is due to the high dust attenuation supported by the large SFRs, the dense large-scale environment as well as large uncertainties in the extinction corrections required to apply when interpreting optical data....

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  67. Very compact millimeter sizes for composite star-forming/AGN submillimeter galaxies

    Soh Ikarashi, Karina Caputi, Kouji Ohta, R. J. Ivison, Claudia D. P. Lagos, Laura Bisigello, Bunyo Hatsukade, Itziar Aretxaga, James S. Dunlop, David H. Hughes, Daisuke Iono, Takuma Izumi, Nobunari Kashikawa, Yusei Koyama, Ryohei Kawabe, Kotaro Kohno, Kentaro Motohara, Kouichiro Nakanishi, Yoichi Tamura, Hideki Umehata, Grant W. Wilson, Kiyoto Yabe, Min S. Yun

    Astrophysical Journal Letters   Vol. 849 ( 2 )   2017.11

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    We report the study of far-IR sizes of submillimeter galaxies (SMGs) in
    relation to their dust-obscured star formation rate (SFR) and active galactic
    nuclei (AGN) presence, determined using mid-IR photometry. We determined the
    millimeter-wave ($\lambda_{\rm obs}=1100 \mu$m) sizes of 69 ALMA-identified
    SMGs, selected with $\geq10$$\sigma$ confidence on ALMA images ($F_{\rm 1100
    \mu m}=1.7$--7.4 mJy). We found that all the SMGs are located above an
    avoidance region in the millimeter size-flux plane, as expected by the
    Eddington limit for star formation. In order to understand what drives the
    different millimeter-wave sizes in SMGs, we investigated the relation between
    millimeter-wave size and AGN fraction for 25 of our SMGs at $z=1$--3. We found
    that the SMGs for which the mid-IR emission is dominated by star formation or
    AGN have extended millimeter-sizes, with respective median $R_{\rm c,e} =
    1.6^{+0.34}_{-0.21}$ and 1.5$^{+0.93}_{-0.24}$ kpc. Instead, the SMGs for which
    the mid-IR emission corresponds to star-forming/AGN composites have more
    compact millimeter-wave sizes, with median $R_{\rm c,e}=1.0^{+0.20}_{-0.20}$
    kpc. The relation between millimeter-wave size and AGN fraction suggests that
    this size may be related to the evolutionary stage of the SMG. The very compact
    sizes for composite star-forming/AGN systems could be explained by supermassive
    black holes growing rapidly during the SMG coalescing, star-formation phase.

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  68. Blind millimeter line emitter search using ALMA data toward gravitational lensing clusters

    Yuki Yamaguchi, Kotaro Kohno, Yoichi Tamura, Masamune Oguri, Hajime Ezawa, Natsuki H. Hayatsu, Tetsu Kitayama, Yuichi Matsuda, Hiroshi Matsuo, Tai Oshima, Naomi Ota, Takuma Izumi, Hideki Umehata

    Astrophysical Journal   Vol. 845 ( 2 )   2017.8

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    We present the results of a blind millimeter line emitter search using ALMA
    Band 6 data with a single frequency tuning toward four gravitational lensing
    clusters (RXJ1347.5-1145, Abell S0592, MACS J0416.1-2403, and Abell 2744). We
    construct three-dimensional signal-to-noise ratio (S/N) cubes with 60 MHz and
    100 MHz binning, and search for millimeter line emitters. We do not detect any
    line emitters with a peak S/N > 5, although we do find a line emitter candidate
    with a peak S/N ~ 4.5. These results provide upper limits to the CO(3-2),
    CO(4-3), CO(5-4), and [CII] luminosity functions at z ~ 0.3, 0.7, 1.2, and 6,
    respectively. Because of the magnification effect of gravitational lensing
    clusters, the new data provide the first constraints on the CO and [CII]
    luminosity functions at unprecedentedly low luminosity levels, i.e., down to
    $<~ 10^{-3}-10^{-1} $Mpc$^{-3}$ dex$^{-1}$ at $L'_{CO} ~ 10^8-10^{10}$ K km
    $s^{-1}$ pc$^2$ and $<~ 10^{-3}-10^{-2}$ Mpc$^{-3}$ dex$^{-1}$ at $L_[CII] ~
    10^8-10^{10} L_\odot$, respectively. Although the constraints to date are not
    stringent yet, we find that the evolution of the CO and [CII] luminosity
    functions are broadly consistent with the predictions of semi-analytical
    models. This study demonstrates that the wide observations with a single
    frequency tuning toward gravitational lensing clusters are promising for
    constraining the CO and [CII] luminosity functions.

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  69. Bimodal morphologies of massive galaxies at the core of a protocluster at z=3.09 and the strong size growth of a brightest cluster galaxy

    M. Kubo, T. Yamada, T. Ichikawa, M. Kajisawa, Y. Matsuda, I. Tanaka, H. Umehata

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 469 ( 2 ) page: 2235 - 2250   2017.8

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    We present the near-infrared high-resolution imaging of an extremely dense group of galaxies at the core of the protocluster at z = 3.09 in the SSA22 field by using the adaptive optics AO188 and the Infrared Camera and Spectrograph on board the Subaru Telescope. The wide morphological variety of them suggests their ongoing dramatic evolutions. One of the two quiescent galaxies (QGs), the most massive one in the group, is a compact elliptical with an effective radius r(e) = 1.37 +/- 0.75 kpc. It supports the two-phase formation scenario of giant ellipticals today that a massive compact elliptical is formed at once and evolves in size and stellar mass by a series of mergers. Since this object is a plausible progenitor of a brightest cluster galaxy of one of the most massive clusters today, it requires strong size (greater than or similar to 10) and stellar mass (similar to four times by z = 0) growths. Another QG hosts an active galactic nucleus and is fitted with a model composed from a nuclear component and Sersic model. It shows a spatially extended [O III] lambda 5007 emission line compared to the continuum emission, plausible evidence of outflows. Massive star-forming galaxies (SFGs) in the group are two to three times larger than the field SFGs at similar redshift. Although we obtained the K-band image deeper than the previous one, we found no new candidate members. This implies a physical deficiency of low-mass galaxies with stellar mass M-* less than or similar to 4 x 10(10) M-circle dot and/or poor detection completeness of them owing to their diffuse morphologies.

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  70. A radio-to-mm census of star-forming galaxies in protocluster 4C23.56 at z=2.5 : Gas mass and its fraction revealed with ALMA

    Minju M. Lee, Ichi Tanaka, Ryohei Kawabe, Kotaro Kohno, Tadayuki Kodama, Masaru Kajisawa, Min S. Yun, Kouichiro Nakanishi, Daisuke Iono, Yoichi Tamura, Bunyo Hatsukade, Hideki Umehata, Toshiki Saito, Takuma Izumi, Itziar Aretxaga, Ken-ichi Tadaki, Milagros Zeballos, Soh Ikarashi, Grant W. Wilson, David H. Hughes, R. J. Ivison

    Astrophysical Journal   Vol. 842 ( 1 )   2017.6

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    We investigate gas contents of star-forming galaxies associated with
    protocluster 4C23.56 at z = 2.49 by using the redshifted CO(3-2) and 1.1 mm
    dust continuum with the Atacama Large Millimeter/submillimeter Array. The
    observations unveil seven CO detections out of 22 targeted H$\alpha$ emitters
    (HAEs) and four out of 19 in 1.1 mm dust continuum. They have high stellar mass
    ($M_{\star}>4\times 10^{10}$ $M_{\odot}$) and exhibit a specific star-formation
    rate typical of main-sequence star forming galaxies at $z\sim2.5$. Different
    gas mass estimators from CO(3-2) and 1.1 mm yield consistent values for
    simultaneous detections. The gas mass ($M_{\rm gas}$) and gas fraction ($f_{\rm
    gas}$) are comparable to those of field galaxies, with $M_{\rm gas}=[0.3,
    1.8]\times10^{11} \times (\alpha_{\rm CO}/(4.36\times A(Z)$)) M$_{\odot}$,
    where $\alpha_{\rm CO}$ is the CO-to-H$_2$ conversion factor and $A(Z)$ the
    additional correction factor for the metallicity dependence of $\alpha_{\rm
    CO}$, and $\langle f_{\rm gas}\rangle = 0.53 \pm 0.07$ from CO(3-2). Our
    measurements place a constraint on the cosmic gas density of high-$z$
    protoclusters, indicating the protocluster is characterized by a gas density
    higher than that of the general fields by an order of magnitude. We found $\rho
    (H_2)\sim 5 \times 10^9 \,M_{\odot}\,{\rm Mpc^{-3 } }$ with the CO(3-2)
    detections. The five ALMA CO detections occur in the region of highest galaxy
    surface density, where the density positively correlates with global
    star-forming efficiency (SFE) and stellar mass. Such correlations imply a
    potentially critical role of environment on early galaxy evolution at high-z
    protoclusters, although future observations are necessary for confirmation.

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  71. Imaging of diffuse HI absorption structure in the SSA22 protocluster region at z=3.1

    Ken Mawatari, Akio K. Inoue, Toru Yamada, Tomoki Hayashino, Takuya Otsuka, Yuichi Matsuda, Hideki Umehata, Masami Ouchi, Shiro Mukae

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 467 ( 4 ) page: 3951 - 3962   2017.6

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    Using galaxies as background light sources to map intervening Ly a absorption is a novel approach to study the interplay among galaxies, the circumgalactic medium (CGM) and the intergalactic medium. Introducing a new measure of z = 3.1 HI Ly alpha absorption relative to the cosmic mean, Delta NB497, estimated from photometric data of star-forming galaxies at 3.3 less than or similar to z less than or similar to 3.5, we have made two-dimensional Delta NB497 maps in the z = 3.1 SSA22 protocluster region and two control fields (Subaru/XMM-Newton Deep Survey; Great Observatory Optical Deep Survey North) with a spatial resolution of similar to 5 comoving Mpc. The Delta NB497 measurements in the SSA22 field are systematically larger than those in the control fields, and this HI absorption enhancement extends more than 50 comovingMpc. The field-averaged (i. e. similar to 50 comovingMpc scale) Delta NB497 and the overdensity of Ly alpha emitters (LAEs) seem to be correlated, while there is no clear dependency of the Delta NB497 on the local LAE overdensity in a few comoving Mpc scale. These results suggest that diffuse HI gas spreads out in/around the SSA22 protocluster. We have also found an enhancement of Delta NB497 at a projected distance &lt; 100 physical kpc from the nearest z = 3.1 galaxies at least in the SSA22 field, which is probably due to HI gas associated with the CGM of individual galaxies. The HI absorption enhancement in the CGM-scale tends to be weaker around galaxies with stronger Ly alpha emission, which suggests that the Ly alpha escape fraction from galaxies depends on hydrogen neutrality in the CGM.

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  72. ALMA deep field in SSA22: Blindly detected CO emitters and [C II] emitter candidates

    Hayatsu, Natsuki H., Matsuda, Yuichi, Umehata, Hideki, Yoshida, Naoki, Smail, Ian, Swinbank, A. Mark, Ivison, Rob, Kohno, Kotaro, Tamura, Yoichi, Kubo, Mariko, Iono, Daisuke, Hatsukade, Bunyo, Nakanishi, Kouichiro, Kawabe, Ryohei, Nagao, Tohru, Inoue, Akio K., Takeuchi, Tsutomu T., Lee, Minju, Ao, Yiping, Fujimoto, Seiji, Izumi, Takuma, Yamaguchi, Yuki, Ikarashi, Soh, Yamada, Toru

    Publications of the Astronomical Society of Japan   Vol. 69 ( 3 )   2017.6

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    We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin<SUP>2</SUP>, frequency ranges of 253.1-256.8 and 269.1-272.8 GHz, angular resolution of 0{^''<SUB>.</SUB>}7 and rms noise of 0.8 mJy beam<SUP>-1</SUP> at 36 km s<SUP>-1</SUP> velocity resolution. We detect four line-emitter candidates with significance levels above 6σ. We identify one of the four sources as a CO(9-8) emitter at z = 3.1 in a member of the proto-cluster known in this field. Another line emitter with an optical counterpart is likely a CO(4-3) emitter at z = 0.7. The other two sources without any millimeter continuum or optical/near-infrared counterpart are likely to be [C II] emitter candidates at z = 6.0 and 6.5. The equivalent widths of the [C II] candidates are consistent with those of confirmed high-redshift [C II] emitters and candidates, and are a factor of 10 times larger than that of the CO(9-8) emitter detected in this search. The [C II] luminosity of the candidates are 4-7 × 10<SUP>8</SUP> L<SUB>☉</SUB>. The star formation rates (SFRs) of these sources are estimated to be 10-20 M<SUB>☉</SUB> yr<SUP>-1</SUP> if we adopt an empirical [C II] luminosity-SFR relation. One of them has a relatively low S/N ratio, but shows features characteristic of emission lines. Assuming that at least one of the two candidates is a [C II] emitter, we derive a lower limit of [C II]-based star formation rate density (SFRD) at z ̃ 6. The resulting value of &gt;10<SUP>-2</SUP> M<SUB>☉</SUB> yr<SUP>-1</SUP> Mpc<SUP>-3</SUP> is consistent with the dust-uncorrected UV-based SFRD. Future millimeter/submillimeter surveys can be used to detect a number of high-redshift line emitters, with which to study the star formation history in the early universe....

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  73. Extremely Red Submillimeter Galaxies: New z>~4-6 Candidates Discovered using ALMA and Jansky VLA

    Soh Ikarashi, R. J. Ivison, Karina I. Caputi, Koichiro Nakanishi, Claudia D. P. Lagos, M. L. N. Ashby, Itziar Aretxaga, James S. Dunlop, Bunyo Hatsukade, David H. Hughes, Daisuke Iono, Takuma Izumi, Ryohei Kawabe, Kotaro Kohno, Kentaro Motohara, Kouji Ohta, Yoichi Tamura, Hideki Umehata, Grant W. Wilson, Kiyoto Yabe, Min S. Yun

    Astrophysical Journal   Vol. 835 ( 2 )   2017.2

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    We present the detailed characterization of two extremely red submillimeter
    galaxies (SMGs), ASXDF1100.053.1 and 231.1, with the Atacama Large
    Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA).
    These SMGs were selected originally using AzTEC at 1100 micron, and are
    observed by Herschel to be faint at 100--500 micron. Their (sub)millimeter
    colors are as red as -- or redder -- than known z>~5 SMGs; indeed,
    ASXDF1100.053.1 is redder than HFLS 3, which lies at z=6.3. They are also faint
    and red in the near-/mid-infrared: ~1 microJy at IRAC 4.5 micron and <0.2
    microJy in the Ks filter. These SMGs are also faint in the radio waveband,
    where F_6GHz=4.5 microJy for ASXDF1100.053.1 and F_1.4GHz=28 microJy for
    ASXDF1100.231.1, suggestive of z=6.5^{+1.4}_{-1.1} and z=4.1^{+0.6}_{-0.7} for
    ASXDF1100.053.1 and 231.1, respectively. ASXDF1100.231.1 has a flux excess in
    the 3.6-micron filter, probably due to H$\alpha$ emission at z=4--5. Derived
    properties of ASXDF1100.053.1 for z=5.5--7.5 and 231.1 for z=3.5--5.5 are as
    follows: their infrared luminosities are [6.5-7.4]x10^{12} and
    [4.2-4.5]x10^{12} L_sun; their stellar masses are [0.9-2]x10^{11} and
    [0.4-3]x10^{10} M_sun; their circularized half-light radii in the ALMA maps are
    ~1 and <~0.2 kpc (~2--3 kpc for 90% of the total flux). Lastly, their surface
    infrared luminosity densities, Sigma_IR, are ~1x10^{12} and >~1.5x10^{13} L_sun
    kpc^{-2}, similar to values seen for local (U)LIRGs. These data suggest that
    ASXDF1100.053.1 and 231.1 are compact SMGs at z>~4 and can plausibly evolve
    into z>~3 compact quiescent galaxies.

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  74. ALMA Deep Field in SSA22: Source Catalog and Number Counts

    Hideki Umehata, Yoichi Tamura, Kotaro Kohno, R. J. Ivison, Ian Smail, Bunyo Hatsukade, Kouichiro Nakanishi, Yuta Kato, Soh Ikarashi, Yuichi Matsuda, Seiji Fujimoto, Daisuke Iono, Minju Lee, Charles C. Steidel, Tomoki Saito, D. M. Alexander, Min S. Yun, Mariko Kubo

    Astrophysical Journal   Vol. 835 ( 1 )   2017.1

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    We present results from a deep 2'x3' (comoving scale of 3.7 Mpc x 5.5 Mpc at
    z=3) survey at 1.1 mm taken with the Atacama Large Millimeter/submillimeter
    Array (ALMA) in the SSA22 field. We observe the core region of a z = 3.09
    protocluster, achieving a typical rms sensitivity of 60 micro-Jy/beam at a
    spatial resolution of 0".7. We detect 18 robust ALMA sources at a
    signal-to-noise ratio (SNR) > 5. Comparison between the ALMA map and a 1.1 mm
    map taken with the AzTEC camera on the Atacama Submillimeter Telescope
    Experiment (ASTE) indicates that three submillimeter sources discovered by the
    AzTEC/ASTE survey are resolved into eight individual submillimeter galaxies
    (SMGs) by ALMA. At least ten of our 18 ALMA SMGs have spectroscopic redshifts
    of z = 3.09, placing them in the protocluster. This shows that a number of
    dusty starburst galaxies are forming simultaneously in the core of the
    protocluster. The nine brightest ALMA SMGs with SNR > 10 have a median
    intrinsic angular size of 0".32+0".13-0".06 (2.4+1.0-0.4 physical kpc at z =
    3.09), which is consistent with previous size measurements of SMGs in other
    fields. As expected the source counts show a possible excess compared to the
    counts in the general fields at S_1.1mm >= 1.0 mJy due to the protocluster. Our
    contiguous mm mapping highlights the importance of large-scale structures on
    the formation of dusty starburst galaxies.

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  75. ALMA reveals Strong [CII] emission in a galaxy embedded in a giant Lyman-alpha blob at z=3.1

    Hideki Umehata, Yuichi Matsuda, Yoichi Tamura, Kotaro Kohno, Ian Smail, R. J. Ivison, Charles C. Steidel, Scott C. Chapman, James E. Geach, Matthew Hayes, Tohru Nagao, Yiping Ao, Ryohei Kawabe, Min S. Yun, Bunyo Hatsukade, Mariko Kubo, Yuta Kato, Tomoki Saito, Soh Ikarashi, Kouichiro Nakanishi, Minju Lee, Takuma Izumi, Masao Mori, Masami Ouchi

    Astrophysical Journal Letters   Vol. 834 ( 2 )   2017.1

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    We report the result from observations conducted with the Atacama Large
    Millimeter/submillimeter Array (ALMA) to detect [CII] 158 um fine structure
    line emission from galaxies embedded in one of the most spectacular Lyman-alpha
    blobs (LABs) at z=3.1, SSA22-LAB1. Of three dusty star-forming galaxies
    previously discovered by ALMA 860 um dust continuum survey toward SSA22-LAB1,
    we detected the [CII] line from one, LAB1-ALMA3 at z=3.0993+/-0.0004. No line
    emission was detected, associated with the other ALMA continuum sources or from
    three rest-frame UV/optical selected z_spec~3.1 galaxies within the field of
    view. For LAB1-ALMA3, we find relatively bright [CII] emission compared to the
    infrared luminosity (L_[CII]/L_[CII]) and an extremely high [CII] 158 um and
    [NII] 205 um emission line ratio (L_[CII]/L_[NII]>55). The relatively strong
    [CII] emission may be caused by abundant photodissociation regions and
    sub-solar metallicity, or by shock heating. The origin of the unusually strong
    [CII] emission could be causally related to the location within the giant LAB,
    although the relationship between extended Lyman-alpha emission and ISM
    conditions of associated galaxies is yet to be understand.

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  76. THE SXDF-ALMA 2 arcmin2DEEP SURVEY: STACKING REST-FRAME NEAR-INFRARED SELECTED OBJECTS Reviewed

    Wang, Wei-Hao, Kohno, Kotaro, Hatsukade, Bunyo, Umehata, Hideki, Aretxaga, Itziar, Hughes, David, Caputi, Karina I, Dunlop, James S, Ikarashi, Soh, Iono, Daisuke, Ivison, Rob J, Lee, Minju, Makiya, Ryu, Matsuda, Yuichi, Motohara, Kentaro, Nakanish, Kouichiro, Ohta, Kouji, Tadaki, Ken-ichi, Tamura, Yoichi, Kodama, Tadayuki, Rujopakarn, Wiphu, Wilson, Grant W, Yamaguchi, Yuki, Yun, Min S, Coupon, Jean, Hsieh, Bau-Ching, Foucaud, Sebastien

    The Astrophysical Journal   Vol. 833 ( 2 ) page: 195   2016.12

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  77. SXDF-ALMA 2 Arcmin^2 Deep Survey: Resolving and Characterizing the Infrared Extragalactic Background Light Down to 0.5 mJy

    Yuki Yamaguchi, Yoichi Tamura, Kotaro Kohno, Itziar Aretxaga, James S. Dunlop, Bunyo Hatsukade, David Hughes, Soh Ikarashi, Shun Ishii, Rob J. Ivison, Takuma Izumi, Ryohei Kawabe, Tadayuki Kodama, Minju Lee, Ryu Makiya, Yuichi Matsuda, Kouichiro Nakanishi, Kouji Ohta, Wiphu Rujopakarn, Ken-ichi Tadaki, Hideki Umehata, Wei-Hao Wang, Grant W. Wilson, Kiyoto Yabe, Min S. Yun

    Publications of the Astronomical Society of Japan   Vol. 68 ( 5 )   2016.10

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    We present a multi-wavelength analysis of five submillimeter sources (S_1.1mm
    = 0.54-2.02 mJy) that were detected during our 1.1-mm-deep continuum survey in
    the SXDF-UDS-CANDELS field (2 arcmin^2, 1sigma = 0.055 mJy beam^-1) using the
    Atacama Large Millimeter/submillimeter Array (ALMA). The two brightest sources
    correspond to a known single-dish (AzTEC) selected bright submillimeter galaxy
    (SMG), whereas the remaining three are faint SMGs newly uncovered by ALMA. If
    we exclude the two brightest sources, the contribution of the ALMA-detected
    faint SMGs to the infrared extragalactic background light is estimated to be ~
    4.1^{+5.4}_{-3.0} Jy deg^{-2}, which corresponds to ~ 16^{+22}_{-12}% of the
    infrared extragalactic background light. This suggests that their contribution
    to the infrared extragalactic background light is as large as that of bright
    SMGs. We identified multi-wavelength counterparts of the five ALMA sources. One
    of the sources (SXDF-ALMA3) is extremely faint in the optical to near-infrared
    region despite its infrared luminosity (L_IR ~ 1e12 L_sun or SFR ~ 100 M_sun
    yr^{-1}). By fitting the spectral energy distributions (SEDs) at the
    optical-to-near-infrared wavelengths of the remaining four ALMA sources, we
    obtained the photometric redshifts (z_photo) and stellar masses (M_*): z_photo
    ~ 1.3-2.5, M_* ~ (3.5-9.5)e10 M_sun. We also derived their star formation rates
    (SFRs) and specific SFRs (sSFRs) as ~ 30-200 M_sun yr^{-1} and ~ 0.8-2
    Gyr^{-1}, respectively. These values imply that they are main-sequence
    star-forming galaxies.

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  78. ALMA observations of a z approximate to 3.1 protocluster: star formation from active galactic nuclei and Lyman-alpha blobs in an overdense environment

    D. M. Alexander, J. M. Simpson, C. M. Harrison, J. R. Mullaney, I. Smail, J. E. Geach, R. C. Hickox, N. K. Hine, A. Karim, M. Kubo, B. D. Lehmer, Y. Matsuda, D. J. Rosario, F. Stanley, A. M. Swinbank, H. Umehata, T. Yamada

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 461 ( 3 ) page: 2944 - 2952   2016.9

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    We exploit Atacama Large Interferometer Array (ALMA) 870 mu m observations to measure the star formation rates (SFRs) of eight X-ray detected active galactic nuclei (AGNs) in a z approximate to 3.1 protocluster, four of which reside in extended Ly alpha haloes (often termed Lymanalpha blobs: LABs). Three of the AGNs are detected by ALMA and have implied SFRs of approximate to 220-410 M-circle dot yr(-1); the non-detection of the other five AGNs places SFR upper limits of approximate to 210 M-circle dot yr(-1). The mean SFR of the protocluster AGNs (approximate to 110-210 M-circle dot yr(-1)) is consistent (within a factor of approximate to 0.7-2.3) with that found for co-eval AGNs in the field, implying that the galaxy growth is not significantly accelerated in these systems. However, when also considering ALMA data from the literature, we find evidence for elevated mean SFRs (up-to a factor of approximate to 5.9 over the field) for AGNs at the protocluster core, indicating that galaxy growth is significantly accelerated in the central regions of the protocluster. We also show that all of the four protocluster LABs are associated with an ALMA counterpart within the extent of their Ly alpha emission. The SFRs of the ALMA sources within the LABs (approximate to 150-410 M-circle dot yr(-1)) are consistent with those expected for co-eval massive star-forming galaxies in the field. Furthermore, the two giant LABs (with physical extents of greater than or similar to 100 kpc) do not host more luminous star formation than the smaller LABs, despite being an order of magnitude brighter in Ly alpha emission. We use these results to discuss star formation as the power source of LABs.

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  79. Clumpy and Extended Starbursts in the Brightest Unlensed Submillimeter Galaxies

    Daisuke Iono, Min S. Yun, Itziar Aretxaga, Bunyo Hatsukade, David Hughes, Soh Ikarashi, Takuma Izumi, Ryohei Kawabe, Kotaro Kohno, Minju Lee, Yuichi Matsuda, Kouichiro Nakanishi, Toshiki Saito, Yoichi Tamura, Junko Ueda, Hideki Umehata, Grant Wilson, Tomonari Michiyama, Misaki Ando

    Astrophysical Journal Letters   Vol. 829 ( 1 )   2016.9

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    The central structure in three of the brightest unlensed z=3-4 submillimeter
    galaxies are investigated through 0.015" - 0.05" (120 -- 360~pc) 860 micron
    continuum images obtained using the Atacama Large Millimeter/submillimeter
    Array (ALMA). The distribution in the central kpc in AzTEC1 and AzTEC8 are
    extremely complex, and they are composed of multiple ~200 pc clumps. AzTEC4
    consists of two sources that are separated by ~1.5 kpc, indicating a mid-stage
    merger. The peak star formation rate densities in the central clumps are ~300 -
    3000 Msun/yr/kpc^2, suggesting regions with extreme star formation near the
    Eddington Limit. By comparing the flux obtained by ALMA and Submillimeter Array
    (SMA), we find that 68-90% of the emission is extended (> 1 kpc) in AzTEC 4 and
    8. For AzTEC1, we identify at least 11 additional compact (~200 pc) clumps in
    the extended 3 - 4 kpc region. Overall, the data presented here suggest that
    the luminosity surface densities observed at < 150 pc scales are roughly
    similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220.
    Between 10 to 30% of the 860 micron continuum is concentrated in clumpy
    structures in the central kpc while the remaining flux is distributed over > 1
    kpc regions, some of which could also be clumpy. These sources can be explained
    by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by
    extended and clumpy starbursts. However, the cold mode accretion model is not
    ruled out.

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  80. Herschel protocluster survey: a search for dusty star-forming galaxies in protoclusters at z = 2-3

    Kato, Y., Matsuda, Y., Smail, Ian, Swinbank, A. M., Hatsukade, B., Umehata, H., Tanaka, I., Saito, T., Iono, D., Tamura, Y., Kohno, K., Erb, D. K., Lehmer, B. D., Geach, J. E., Steidel, C. C., Alexander, D. M., Yamada, T., Hayashino, T.

    Monthly Notices of the Royal Astronomical Society   Vol. 460 ( 4 ) page: 3861 - 3872   2016.8

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    We present a Herschel/Spectral and Photometric Imaging Receiver (SPIRE) survey of three protoclusters at z = 2-3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours (S<SUB>350</SUB>/S<SUB>250</SUB> and S<SUB>500</SUB>/S<SUB>350</SUB>) of 250 μm sources, we selected high-redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4σ overdensity of six SPIRE sources around 4.5 arcmin (̃2.2 Mpc) from a density peak of H α emitters at z = 2.2. In the HS1700 field, we found a 5σ overdensity of eight SPIRE sources around 2.1 arcmin (̃1.0 Mpc) from a density peak of Lyman-break galaxies at z = 2.3. We did not find any significant overdensities in SSA22 field, but we found three 500 μm sources are concentrated 3 arcmin (̃1.4 Mpc) east to the Ly α emitters overdensity. If all the SPIRE sources in these three overdensities are associated with protoclusters, the inferred star formation rate densities are 10<SUP>3</SUP>-10<SUP>4</SUP> times higher than the average value at the same redshifts. This suggests that dusty star formation activity could be very strongly enhanced in z ̃ 2-3 protoclusters. Further observations are needed to confirm the redshifts of the SPIRE sources and to investigate what processes enhance the dusty star formation activity in z ̃ 2-3 protoclusters....

    DOI: 10.1093/mnras/stw1237

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  81. Detection of an oxygen emission line from a high redshift galaxy in the reionization epoch

    Akio K. Inoue, Yoichi Tamura, Hiroshi Matsuo, Ken Mawatari, Ikkoh Shimizu, Takatoshi Shibuya, Kazuaki Ota, Naoki Yoshida, Erik Zackrisson, Nobunari Kashikawa, Kotaro Kohno, Hideki Umehata, Bunyo Hatsukade, Masanori Iye, Yuichi Matsuda, Takashi Okamoto, Yuki Yamaguchi

    Science   Vol. 352 ( 6293 ) page: 1559 - 1562   2016.6

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    The physical properties and elemental abundances of the interstellar medium
    in galaxies during cosmic reionization are important for understanding the role
    of galaxies in this process. We report the Atacama Large
    Millimeter/submillimeter Array detection of an oxygen emission line at a
    wavelength of 88 micrometers from a galaxy at an epoch about 700 million years
    after the Big Bang. The oxygen abundance of this galaxy is estimated at about
    one-tenth that of the Sun. The non-detection of far-infrared continuum emission
    indicates a deficiency of interstellar dust in the galaxy. A carbon emission
    line at a wavelength of 158 micrometers is also not detected, implying an
    unusually small amount of neutral gas. These properties might allow ionizing
    photons to escape into the intergalactic medium.

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  82. SXDF–ALMA 2-arcmin2deep survey: 1.1-mm number counts Reviewed

    Hatsukade, B, Kohno, K, Umehata, H, Aretxaga, I, Caputi, K. I, Dunlop, J. S, Ikarashi, S, Iono, D, Ivison, R. J, Lee, M, Makiya, R, Matsuda, Y, Motohara, K, Nakanishi, K, Ohta, K, Tadaki, K.-i, Tamura, Y, Wang, W.-H, Wilson, G. W, Yamaguchi, Y, Yun, M. S

    Publications of the Astronomical Society of Japan   Vol. 68 ( 3 ) page: 36   2016.6

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    DOI: 10.1093/pasj/psw026

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  83. 学部生に伝える研究最前線

    関根 康人, 伊藤 恭子, 福田 裕穂, 梅畑 豪紀, 田村 陽一, 河野 孝太郎

    東京大学理学系研究科・理学部ニュース   Vol. 47 ( 6 ) page: 12 - 14   2016.3

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    土星の衛星エンセラダスに生命を育む海がある!?/自己抑制の仕組みでバランスを保つ植物の根/115億光年かなたの宇宙で見つかった怪物銀河の大集団

    CiNii Research

  84. New Detections of Galactic Molecular Absorption Systems toward ALMA Calibrator Sources

    Ryo Ando, Kotaro Kohno, Yoichi Tamura, Takuma Izumi, Hideki Umehata, Hiroshi Nagai

    Publications of the Astronomical Society of Japan   Vol. 68 ( 1 )   2016.2

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    We report on Atacama Large Millimeter/submillimeter Array (ALMA) detections
    of molecular absorption lines in Bands 3, 6 and 7 toward four radio-loud
    quasars, which were observed as the bandpass and complex gain calibrators. The
    absorption systems, three of which are newly detected, are found to be Galactic
    origin. Moreover, HCO absorption lines toward two objects are detected, which
    almost doubles the number of HCO absorption samples in the Galactic diffuse
    medium. In addition, high HCO to H13CO+ column density ratios are found,
    suggesting that the interstellar media (ISM) observed toward the two
    calibrators are in photodissociation regions, which observationally illustrates
    the chemistry of diffuse ISM driven by ultraviolet (UV) radiation. These
    results demonstrate that calibrators in the ALMA Archive are potential sources
    for the quest for new absorption systems and for detailed investigation of the
    nature of the ISM.

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  85. An extremely dense group of massive galaxies at the centre of the protocluster at z=3.09 in the SSA22 field

    M. Kubo, T. Yamada, T. Ichikawa, M. Kajisawa, Y. Matsuda, I. Tanaka, H. Umehata

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   Vol. 455 ( 3 ) page: 3333 - 3344   2016.1

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    We report the discovery of an extremely dense group of massive galaxies at the centre of the protocluster at z = 3.09 in the SSA22 field from near-infrared spectroscopy conducted with the multi-object infrared camera and spectrograph (MOIRCS) on the Subaru Telecope. The newly discovered group comprises seven galaxies confirmed at z(spec) approximate to 3.09 within 180 kpc, including fivemassive objectswith the stellarmasses larger than 10(10.5) M-circle dot and is associated with a bright submillimetre source SSA22-AzTEC14. The dynamical mass of the group estimated from the line-of-sight velocity dispersion of the members is M-dyn similar to 1.6 +/- 0.3 x 10(13)M(circle dot). Such a dense group is expected to be very rare at high redshift, as we have found only a few comparable systems in large-volume cosmological simulations. Such rare groups in simulations are hosted in collapsed haloes with M-vir = 10(13.4)-10(14.0)M(circle dot) and evolve into the brightest cluster galaxies (BCGs) of the most massive clusters at present. The observed AzTEC14 group at z = 3.09 is therefore very likely to be a proto-BCG in the multiple merger phase. The observed total stellar mass of the group is 5.8(-2.0)(+5.1) x 10(11)M(circle dot), which suggests that over half the stellar mass of its descendant had been formed by z = 3. Moreover, we have identified over two members for each of the four Ly alpha blobs (LABs) using our new spectroscopic data. This verifies our previous argument that many of the LABs in the SSA22 protocluster associated with multiple developed stellar components.

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  86. SXDF-UDS-CANDELS-ALMA 1.5 arcmin2 deep survey Reviewed

    Kohno, K, Tamura, Y, Yamaguchi, Y, Umehata, H, Rujopakarn, W, Lee, M, Motohara, K, Makiya, R, Izumi, T, Ivison, R, Ikarashi, S, Tadaki, K.-i, Kodama, T, Hatsukade, B, Yabe, K, Hayashi, M, Iono, D, Matsuda, Y, Nakanishi, K, Kawabe, R, Wilson, G, Yun, M. S, Hughes, D, Caputi, K, Dunlop, J

    Proceedings of the International Astronomical Union   Vol. 11 ( S319 ) page: 92 - 95   2016

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    <jats:title>Abstract</jats:title><jats:p>We have conducted 1.1 mm ALMA observations of a contiguous 105” × 50” or 1.5 arcmin<jats:sup>2</jats:sup> window in the SXDF-UDS-CANDELS. We achieved a 5σ sensitivity of 0.28 mJy, giving a flat sensus of dusty star-forming galaxies with <jats:italic>L</jats:italic><jats:sub>IR</jats:sub> ~6×10<jats:sup>11</jats:sup><jats:italic>L</jats:italic><jats:sub>⊙</jats:sub> (if <jats:italic>T</jats:italic><jats:sub>dust</jats:sub>=40K) up to <jats:italic>z</jats:italic> ~ 10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N&gt;6) and 18 low-significant sources (5&gt;S/N&gt;4; they may contain spurious detections, though). One of the 5 brightest ALMA sources (<jats:italic>S</jats:italic><jats:sub>1.1mm</jats:sub> = 0.84 ± 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey uncovers a faint dust-obscured population invisible in the deep optical/near-infrared surveys. We find a possible [CII]-line emitter at <jats:italic>z</jats:italic>=5.955 or a low-<jats:italic>z</jats:italic> CO emitting galaxy within the field, allowing us to constrain the [CII] and/or CO luminosity functions across the history of the universe.</jats:p>

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  87. Dusty Starbursts within a z=3 Large Scale Structure revealed by ALMA

    Umehata, H

    GALAXIES AT HIGH REDSHIFT AND THEIR EVOLUTION OVER COSMIC TIME   Vol. 11 ( S319 ) page: 109 - 109   2016

  88. ALMA DEEP FIELD IN SSA22: A CONCENTRATION OF DUSTY STARBURSTS IN Az= 3.09 PROTOCLUSTER CORE

    H. Umehata, Y. Tamura, K. Kohno, R. J. Ivison, D. M. Alexander, J. E. Geach, B. Hatsukade, D. H. Hughes, S. Ikarashi, Y. Kato, T. Izumi, R. Kawabe, M. Kubo, M. Lee, B. Lehmer, R. Makiya, Y. Matsuda, K. Nakanishi, T. Saito, I. Smail, T. Yamada, Y. Yamaguchi, M. Yun

    The Astrophysical Journal   Vol. 815 ( 1 )   2015.12

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    © 2015. The American Astronomical Society. All rights reserved. We report the results of 1.′5 ×3′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S1.1 mm= 0.7-6.4 mJy (LIR∼ 1012.1-1013.1Lo) are at z = 3.08-3.10. Not only are these SMGs members of the protocluster, but they in fact reside within the node at the junction of the 50 Mpc scale filamentary three-dimensional structure traced by Lyα emitters in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 Moyr-1Mpc-3in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host an X-ray-luminous active galactic nucleus. Our results suggest that the vigorous star formation activity and the growth of supermassive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyα blobs, implying that the two populations coexist in high-density environments for a few cases.

    DOI: 10.1088/2041-8205/815/1/L8

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  89. Protocluster Survey at z = 2.23: from Herschel to ALMA Reviewed

    Kato, Y., Matsuda, Y., Smail, I., Swinbank, M., Alexander, D., Geach, J., Lehmer, B., Tamura, Y., Umehata, H., Kohno, K., Kubo, M., Yamada, T., Hayashino, T., Erb, D., Steidel, C.

    Revolution in Astronomy with ALMA: The Third Year     2015.12

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    We present results of Herschel/SPIRE observation in 2QZ cluster at z=2.23. 2QZ cluster is discovered as an overdensity of QSOs and Hα emitters (HAEs), which was originally identified as a concentration of 5 QSOs in the 2dF Quasar Redshift survey. We find an overdensity of SPIRE color selected far-infrared bright galaxies (3.9 σ compared with COSMOS field) ̃5' west of the HAEs density peak of in a radius of 6 co-Mpc. This suggests 2QZ cluster is experiencing enhanced dusty star-formation. However, SPIRE color selection with S<SUB>500</SUB>/S<SUB>350</SUB> vs S<SUB>350</SUB>/S<SUB>250</SUB> has a redshift uncertainty, we need spectroscopic observation with ALMA to confirm the precise redshifts....

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  90. Dusty Starbursts within a z=3 Large Scale Structure Reviewed

    Umehata, H., Kohno, K., Tamura, Y., Iono, D., Nakanishi, K., Hatsukade, B., Ikarashi, S., Izumi, T., Matsuda, Y., Ivison, R., Yun, M., Wilson, G., Hughes, D.

    Revolution in Astronomy with ALMA: The Third Year     2015.12

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    We present the results of an ALMA survey of submillimeter galaxies (SMGs) in the SSA22 field. Totally 45 sources discovered by the AzTEC/ASTE survey were observed at 1.1mm to find 64 ALMA -identified SMGs with S/N≥4.5. This is the largest SMG survey in Band 6 in ALMA Cycle1. Previous panoramic Lyman-alpha emitter (LAE) surveys have unveiled that SSA22 is not a general field but a highly biased field at z=3.1. We find large excess in the number counts and surface number density compared to the ALESS survey in ECDFS, which suggests SMGs are preferentially formed in the dense environment at z̃3....

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  91. Dusty, Intensively Star Forming Hα Emitters (HAEs) in Protocluster 4C23.56 Reviewed

    Lee, M., Suzuki, K., Kohno, K., Tamura, Y., Iono, D., Hatsukade, B., Nakanishi, K., Tanaka, I., Kodama, T., Tadaki, K., Ikarashi, S., Ueda, J., Umehata, H., Saito, T., Kawabe, R.

    Revolution in Astronomy with ALMA: The Third Year     2015.12

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    We report on the measurements of physical properties of HAEs in protocluster 4C23.56 at z = 2.49 using deep and high resolution observations with ALMA at Band 6 (270 GHz) and JVLA at S-band (3 GHz). We detect four and seven out of 24 HAEs from ALMA and JVLA, and we find that the detected samples are in massive-end (log M<SUB>★</SUB>(M<SUB>☉</SUB>)≳10.1) . We derive extinction-free SFRs and the amount of dust attenuation based on JVLA detections for those without AGN features. The detected HAEs are massive and heavily dust-obscured star forming galaxies. The majority of these HAEs are experiencing burst-like phase. We derive interstellar medium (ISM) masses from the single band ALMA observation and all but one of ALMA detections have ISM mass fractions of ̃ 25% which is a tentatively low value compared to the samples of the general field. This suggests that an accelerated galaxy evolution may have occurred in the over-dense region at this high redshift, though the uncertainty is large. <P />...

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  92. SXDF-ALMA 1.5 arcmin^2 deep survey. A compact dusty star-forming galaxy at z=2.5

    Ken-ichi Tadaki, Kotaro Kohno, Tadayuki Kodama, Soh Ikarashi, Itziar Aretxaga, Stefano Berta, Karina I. Caputi, James S. Dunlop, Bunyo Hatsukade, Masao Hayashi, David H. Hughes, Rob Ivison, Takuma Izumi, Yusei Koyama, Dieter Lutz, Ryu Makiya, Yuichi Matsuda, Kouichiro Nakanishi, Wiphu Rujopakarn, Yoichi Tamura, Hideki Umehata, Wei-Hao Wang, Grant W. Wilson, Stijn Wuyts, Yuki Yamaguchi, Min S. Yun

    Astrophysical Journal Letters   Vol. 811 ( 1 )   2015.9

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    We present first results from the SXDF-ALMA 1.5 arcmin^2 deep survey at 1.1
    mm using Atacama Large Millimeter Array (ALMA). The map reaches a 1sigma depth
    of 55 uJy/beam and covers 12 Halpha-selected star-forming galaxies at z = 2.19
    or z=2.53. We have detected continuum emission from three of our
    Halpha-selected sample, including one compact star-forming galaxy with high
    stellar surface density, NB2315-07. They are all red in the rest-frame optical
    and have stellar masses of log (M*/Msun)>10.9 whereas the other blue,
    main-sequence galaxies with log(M*/Msun)=10.0-10.8 are exceedingly faint, <290
    uJy (2sigma upper limit). We also find the 1.1 mm-brightest galaxy, NB2315-02,
    to be associated with a compact (R_e=0.7+-0.1 kpc), dusty star-forming
    component. Given high gas fraction (44^{+20}_{-8}% or 37^{+25}_{-3}%) and high
    star formation rate surface density (126^{+27}_{-30} Msun yr^{-1}kpc^{-2}), the
    concentrated starburst can within less than 50^{+12}_{-11} Myr build up a
    stellar surface density matching that of massive compact galaxies at z~2,
    provided at least 19+-3% of the total gas is converted into stars in the galaxy
    centre. On the other hand, NB2315-07, which already has such a high stellar
    surface density core, shows a gas fraction (23+-8%) and is located in the lower
    envelope of the star formation main-sequence. This compact less star-forming
    galaxy is likely to be in an intermediate phase between compact dusty
    star-forming and quiescent galaxies.

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  93. ALMA Observations of the Submillimeter Dense Molecular Gas Tracers in the Luminous Type-1 Active Nucleus of NGC 7469

    Takuma Izumi, Kotaro Kohno, Susanne Aalto, Akihiro Doi, Daniel Espada, Kambiz Fathi, Nanase Harada, Bunyo Hatsukade, Takashi Hattori, Pei-Ying Hsieh, Soh Ikarashi, Masatoshi Imanishi, Daisuke Iono, Sumio Ishizuki, Melanie Krips, Sergio Martín, Satoki Matsushita, David S. Meier, Hiroshi Nagai, Naomasa Nakai, Taku Nakajima, Kouichiro Nakanishi, Hideko Nomura, Michael W. Regan, Eva Schinnerer, Kartik Sheth, Shuro Takano, Yoichi Tamura, Yuichi Terashima, Tomoka Tosaki, Jean L. Turner, Hideki Umehata, Tommy Wiklind

    Astrophysical Journal   Vol. 811 ( 1 )   2015.9

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    We present ALMA Cycle 1 observations of the central kpc region of the
    luminous type-1 Seyfert galaxy NGC 7469 with unprecedented high resolution
    (0.5$"$ $\times$ 0.4$"$ = 165 pc $\times$ 132 pc) at submillimeter wavelengths.
    Utilizing the wide-bandwidth of ALMA, we simultaneously obtained HCN(4-3),
    HCO$^+$(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860
    $\mu$m continuum. The region consists of the central $\sim$ 1$"$ component and
    the surrounding starburst ring with a radius of $\sim$ 1.5$"$-2.5$"$. Several
    structures connect these components. Except for CO(3-2), these dense gas
    tracers are significantly concentrated towards the central $\sim$ 1$"$,
    suggesting their suitability to probe the nuclear regions of galaxies. Their
    spatial distribution resembles well those of centimeter and mid-infrared
    continuum emissions, but it is anti-correlated with the optical one, indicating
    the existence of dust obscured star formation. The integrated intensity ratios
    of HCN(4-3)/HCO$^+$(4-3) and HCN(4-3)/CS(7-6) are higher at the AGN position
    than at the starburst ring, which is consistent to our previous findings
    (submm-HCN enhancement). However, the HCN(4-3)/HCO$^+$(4-3) ratio at the AGN
    position of NGC 7469 (1.11$\pm$0.06) is almost half of the corresponding value
    of the low-luminosity type-1 Seyfert galaxy NGC 1097 (2.0$\pm$0.2), despite the
    more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the
    ratio is comparable to that of the close vicinity of the AGN of NGC 1068
    ($\sim$ 1.5). Based on these results, we speculate that some other heating
    mechanisms than X-ray (e.g., mechanical heating due to AGN jet) can contribute
    significantly for shaping the chemical composition in NGC 1097.

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  94. COMPACT STARBURSTS IN z~3–6 SUBMILLIMETER GALAXIES REVEALED BY ALMA Reviewed

    Ikarashi, S, Ivison, R. J, Caputi, K. I, Aretxaga, I, Dunlop, J. S, Hatsukade, B, Hughes, D. H, Iono, D, Izumi, T, Kawabe, R, Kohno, K, Lagos, C. D. P, Motohara, K, Nakanishi, K, Ohta, K, Tamura, Y, Umehata, H, Wilson, G. W, Yabe, K, Yun, M. S

    The Astrophysical Journal   Vol. 810 ( 2 ) page: 133   2015.9

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  95. Protocluster Survey at z=2.23: from Herschel to ALMA

    Kato, Y; Matsuda, Y; Smail, I; Swinbank, M; Alexander, D; Geach, J; Lehmer, B; Tamura, Y; Umehata, H; Kohno, K; Kubo, M; Yamada, T; Hayashino, T; Erb, D; Steidel, C

    REVOLUTION IN ASTRONOMY WITH ALMA: THE THIRD YEAR   Vol. 499   page: 25 - 26   2015

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  96. Dusty Starbursts within a z=3 Large Scale Structure

    Umehata, H; Kohno, K; Tamura, Y; Iono, D; Nakanishi, K; Hatsukade, B; Ikarashi, S; Izumi, T; Matsuda, Y; Ivison, R; Yun, M; Wilson, G; Hughes, D

    REVOLUTION IN ASTRONOMY WITH ALMA: THE THIRD YEAR   Vol. 499   page: 29 - 30   2015

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  97. Dusty, Intensively Star Forming Ha Emitters (HAEs) in Protocluster 4C23.56

    Lee, M; Suzuki, K; Kohno, K; Tamura, Y; Iono, D; Hatsukade, B; Nakanishi, K; Tanaka, I; Kodama, T; Tadaki, K; Ikarashi, S; Ueda, J; Umehata, H; Saito, T; Kawabe, R

    REVOLUTION IN ASTRONOMY WITH ALMA: THE THIRD YEAR   Vol. 499   page: 27 - 28   2015

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  98. AzTEC/ASTE 1.1-mm survey of SSA22: Counterpart identification and photometric redshift survey of submillimetre galaxies

    Umehata, H., Tamura, Y., Kohno, K., Hatsukade, B., Scott, K. S., Kubo, M., Yamada, T., Ivison, R. J., Cybulski, R., Aretxaga, I., Austermann, J., Hughes, D. H., Ezawa, H., Hayashino, T., Ikarashi, S., Iono, D., Kawabe, R., Matsuda, Y., Matsuo, H., Nakanishi, K., Oshima, T., Perera, T., Takata, T., Wilson, G. W., Yun, M. S.

    Monthly Notices of the Royal Astronomical Society   Vol. 440 ( 4 ) page: 3462 - 3478   2014.6

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    We present the results from a 1.1-mm imaging survey of the SSA22 field, known for having an overdensity of z = 3.1 Lyman α emitting galaxies (LAEs), taken with the astronomical thermal emission camera (AzTEC) on the Atacama Submillimeter Telescope Experiment (ASTE). We imaged a 950-arcmin<SUP>2</SUP> field down to a 1σ sensitivity of 0.7-1.3 mJy beam<SUP>-1</SUP> to find 125 submillimetre galaxies (SMGs) with a signal-to-noise ratio ≥3.5. Counterpart identification using radio and near/mid-infrared data was performed and one or more counterpart candidates were found for 59 SMGs. Photometric redshifts based on optical to near-infrared images were evaluated for 45 of these SMGs with Spitzer/IRAC data and the median value is found to be z = 2.4. By combining these estimations with estimates from the literature, we determined that 10 SMGs might lie within the large-scale structure at z = 3.1. The two-point angular cross-correlation function between LAEs and SMGs indicates that the positions of the SMGs are correlated with the z = 3.1 protocluster. These results suggest that the SMGs were formed and evolved selectively in the high dense environment of the high-redshift Universe. This picture is consistent with the predictions of the standard model of hierarchical structure formation....

    DOI: 10.1093/mnras/stu447

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  99. 287-288 Jansky VLA S-band view of Hα emitters (HAEs) associated with a protocluster 4C23.56 at z = 2.5

    Minju Lee, Kenta Suzuki, Kotaro Kohno, Yoichi Tamura, Daisuke Iono, Bunyo Hatsukade, Kouichiro Nakanishi, Ichi Tanaka, Tadayuki Kodama, Kenichi Tadaki, Soh Ikarashi, Junko Ueda, Hideki Umehata, Toshiki Saito, Ryohei Kawabe

    Proceedings of the International Astronomical Union   Vol. 10 ( 309 ) page: 287 - 288   2014

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:Cambridge University Press  

    We present recent results on Karl Jansky Very Large Array (JVLA) deep S-band (2-4 GHz) observation towards a protocluster 4C23.56 at redshift z ∼ 2.5. The protocluster 4C23.56 is known to have a significant over density (∼ 5 times) of star-burst galaxies selected to be Hα line-bright by a Subaru narrow band imaging. Now we have found 25 HAEs associated with the protocluster. These starburst HAEs are likely to become massive ellipticals at z = 0 in a cluster. Various other galaxy populations also reside in this field and the fact makes the field very unique as a tool to understand galaxy formation in a over dense region. Subsequent deep 1100-μm continuum surveys by the ASTE 10-m dish have discovered that several submillimeter bright galaxies (SMGs) coincide with HAEs, suggesting HAEs undergoing dusty starbursts. As star formation rates (SFRs) of HAEs might have been underestimated, we use radio being resistant to dust extinction. We investigate the correlation between SFR1.4GHz and SFRHα for radio index α = 0.8 to see if the correlation holds for the sources and to check the number of dusty star forming galaxies. Our final results will allow us to evaluate quantitatively how the galaxy formation channel may be different under the condition of over-densities.

    DOI: 10.1017/S1743921314009892

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  100. Submillimeter Galaxies in the SSA22 Protocluster at z = 3.1 Reviewed

    Umehata, H., Tamura, Y., Kohno, K.

    New Trends in Radio Astronomy in the ALMA Era: The 30th Anniversary of Nobeyama Radio Observatory     2013.10

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    We present the results from the 1.1mm continuum imaging the SSA22 field, which is known as an protocluster field which is traced by Lyα emitting galaxies (LAEs) at z = 3.1, with the AzTEC camera on ASTE telescope. We find 112 submillimeter(1.1mm)-selected galaxies (SMGs) with signal to noise ratio of ≥3.5 within 50% coverage region. Counterpart identification analysis utilizing radio(1.4GHz), MIPS ch1(24 μm) imaging data and IRAC color(3.6 μm, 4.5 μm, 5.8 μm, and 8.0 μm) diagnostics has been carried out to reveal that 48 SMGs have at least one reliable counterpart. We derived photometric redshifts of these sources and consequently seven z = 3.1 candidate SMGs are extracted. Two point angular correlation function between LAEs and these SMGs indicate that high density regions at the high redshift universe are the site of SMG/AGN formation. This picture is consistent with predictions from the standard model of hierarchical structure formation. <P />...

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  101. Sub-mm Singledish and Interferometric Observations of the Proto-Cluster around 4C 23.56 at z = 2.5 Reviewed

    Suzuki, K., Kohno, K., Tanaka, I., Kodama, T., Hatsukade, B., Tamura, Y., Nakanishi, K., Iono, D., Kajisawa, M., Ikarashi, S., Umehata, H., Ivison, R. J., Wilson, G. W., Yun, M. S., Hughes, D. H., Aretxaga, I., Zeballos, M.

    New Trends in Radio Astronomy in the ALMA Era: The 30th Anniversary of Nobeyama Radio Observatory     2013.10

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    We investigate the association of multiple mm-bright galaxies to the proto-cluster around 4C 23.56 at z = 2.48 by the combined observation of the AzTEC/ASTE singledish and the Plateau de Bure Interferometer. We detected 1.8 mm emissions from four HAEs associated with this proto-cluster, and detected CO line from two of them. From these observed values, we investigated their star formation rates (SFRs) and variation in mass compositions. Their SFRs are estimated as 60 to 690 M<SUB>☉</SUB> yr<SUP>-1</SUP> from their submm-mm fluxes. SFRs from mm fluxes for three HAEs are comparable to SFRs from extinction corrected Hα luminosity, but only for HAE 431, large discrepancy in two SFR estimators is seen and large star formation should be dust-obscured....

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  102. Obscured star formation in Ly-alpha blobs at z = 3.1

    Yoichi Tamura, Yuichi Matsuda, Soh Ikarashi, Kimberly S. Scott, Bunyo Hatsukade, Hideki Umehata, Tomoki Saito, Kouichiro Nakanishi, Min S. Yun, Hajime Ezawa, David H. Hughes, Daisuke Iono, Ryohei Kawabe, Kotaro Kohno, Grant W. Wilson

    Monthly Notices of the Royal Astronomical Society   Vol. 430 ( 4 ) page: 2768 - 2773   2013.4

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    We present results from the AzTEC/ASTE 1.1-mm imaging survey of 35 Ly-alpha
    blobs (LABs) found in the SSA22 protocluster at z = 3.1. These 1.1-mm data
    reach an r.m.s. noise level of 0.7-1 mJy/beam, making this the largest
    millimetre-wave survey of LABs to date. No significant (> 3.5-sigma) emission
    is found in any of individual 35 LABs, and from this, we estimate 3-sigma upper
    limits on the far-infrared luminosity of L_FIR < 2e+12 Lsun. Stacking analysis
    reveals that the 1.1-mm flux density averaged over the LABs is S(1.1mm) < 0.40
    mJy (3-sigma), which places a constraint of L_FIR < 4.5e+11 Lsun. This
    indicates that earlier 850-um measurements of the LABs may have overestimated
    their flux densities. Our results suggest that LABs on average have little
    ultra-luminous obscured star-formation, in contrast to a long-believed picture
    that LABs undergo an intense episode of dusty star-formation activities with
    star-formation rates of ~ 10^3 Msun/yr. Observations with ALMA are needed to
    directly study the obscured part of star-formation activity in the LABs.

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  103. Submillimeter Galaxies in the SSA22 Protocluster at <i>z</i>=3.1

    Umehata, H; Tamura, Y; Kohno, K

    NEW TRENDS IN RADIO ASTRONOMY IN THE ALMA ERA: THE 30TH ANNIVERSARY OF NOBEYAMA RADIO OBSERVATORY   Vol. 476   page: 271 - 272   2013

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  104. AzTEC/ASTE Deep and Wide Submillimeter Galaxy Survey in the Subaru/XMM-Newton Deep Field: Identification of VLA, Spitzer and Herschel Counterparts to 1100-&mu;m-Selected Galaxies and Redshifts

    Ikarashi, S, Kohno, K, Aretxaga, I, Arumugam, V, Caputi, K, Dunlop, J, Hatsukade, B, Hughes, D, Iono, D, Ivison, R, Kawabe, R, Motohara, K, Nakanishi, K, Ohta, K, Suzuki, K, Tamura, Y, Umehata, H, Wilson, G, Yabe, K, Yun, M

    New Trends in Radio Astronomy in the ALMA Era: The 30th Anniversary of Nobeyama Radio Observatory   Vol. 476   page: 265   2013

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  105. AzTEC/ASTE Deep and Wide Submillimeter Galaxy Survey in the Subaru/XMM-Newton Deep Field: Identification of VLA, Spitzer and Herschel Counterparts to 1100-μm-Selected Galaxies and Redshifts

    Ikarashi, S; Kohno, K; Aretxaga, I; Arumugam, V; Caputi, K; Dunlop, J; Hatsukade, B; Hughes, D; Iono, D; Ivison, R; Kawabe, R; Motohara, K; Nakanishi, K; Ohta, K; Suzuki, K; Tamura, Y; Umehata, H; Wilson, G; Yabe, K; Yun, M

    NEW TRENDS IN RADIO ASTRONOMY IN THE ALMA ERA: THE 30TH ANNIVERSARY OF NOBEYAMA RADIO OBSERVATORY   Vol. 476   page: 265 - 268   2013

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  106. Sub-mm Singledish and Interferometric Observations of the Proto-Cluster around 4C 23.56 at <i>z</i>=2.5

    Suzuki, K; Kohno, K; Tanaka, I; Kodama, T; Hatsukade, B; Tamura, Y; Nakanishi, K; Iono, D; Kajisawa, M; Ikarashi, S; Umehata, H; Ivison, RJ; Wilson, GW; Yun, MS; Hughes, DH; Aretxaga, I; Zeballos, M

    NEW TRENDS IN RADIO ASTRONOMY IN THE ALMA ERA: THE 30TH ANNIVERSARY OF NOBEYAMA RADIO OBSERVATORY   Vol. 476   page: 263 - 264   2013

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  107. 39th COSPAR Scientific Assembly

      Vol. 106 ( 1 ) page: 62   2012.12

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  108. Initial Results from Nobeyama Molecular Gas Observations of Distant Bright Galaxies

    IONO Daisuke, HATSUKADE Bunyo, KOHNO Kotaro, KAWABE Ryohei, IKARASHI Soh, ICHIKAWA Kohei, KODAMA Tadayuki, MOTOHARA Kentaro, NAKAJIMA Taku, NAKANISHI Koichiro, OHTA Kouji, OTA Kazuaki, SAITO Toshiki, SUZUKI Kenta, TADAKI Ken-ichi, TAMURA Yoichi, UEDA Junko, UMEHATA Hideki, YABE Kiyoto, YOSHIDA Tessei, YUMA Suraphong, KUNO Nario, TAKANO Shuro, IWASHITA Hiroyuki, HANDA Kazuyuki, HIGUCHI Aya, HIROTA Akihiko, ISHIKAWA Shinichi, KIMURA Kimihiro, MAEKAWA Jun, MIKOSHIBA Hiroshi, MIYAZAWA Chieko, MIYAZAWA Kazuhiko, MURAOKA Kazuyuki, OGAWA Hideo, ONODERA Sachiko, SAITO Yasufumi, SAKAI Takeshi, TAKAHASHI Shigeru, YUN Min S.

    Publications of the Astronomical Society of Japan   Vol. 64 ( 4 ) page: "L2 - 1"-"L2-4"   2012.8

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    We present initial results from the CO survey toward high-redshift galaxies using the Nobeyama 45m telescope. Using a new wide bandwidth spectrometer equipped with a two-beam SIS receiver, we have obtained three new detections of high-redshift (z = 1.6-3.4) submillimeter galaxies (SXDF 1100.001/HXMM02, SDP9, and SDP17), one tentative detection (SDSS J160705+533558), and one non-detection (COSMOS-AzTEC1). The galaxies observed during the commissioning phase are sources with known spectroscopic redshifts from previous optical or wide-band submillimeter spectroscopy. The derived molecular gas mass and line widths from Gaussian fits are ∼ 1011M⊙and 430-530km s-1, respectively, which are consistent with previous CO observations of distant submillimeter galaxies and quasars. The spectrometer, which realizes a maximum of 32 GHz instantaneous bandwidth, will provide new science capabilities at the Nobeyama 45m telescope, allowing us to determine redshifts of bright submillimeter selected galaxies without any prior redshift information. © 2012. Astronomical Society of Japan.

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  109. Integral field spectroscopy of 2.0&lt; z&lt;2.7 submillimetre galaxies: gas morphologies and kinematics

    Alaghband-Zadeh, S., Chapman, S. C., Swinbank, A. M., Smail, Ian, Harrison, C. M., Alexander, D. M., Casey, C. M., Davé, R., Narayanan, D., Tamura, Y., Umehata, H.

    Monthly Notices of the Royal Astronomical Society   Vol. 424 ( 3 ) page: 2232 - 2248   2012.8

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    We present 2D, integral field spectroscopy covering the rest-frame wavelengths of strong optical emission lines in nine submillimetre luminous galaxies (SMGs) at 2.0 &lt; z &lt; 2.7. The Gemini-North/Near-Infrared Integral Field Spectrograph (NIFS) and Very Large Telescope (VLT) Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) imaging spectroscopy allow the mapping of the gas morphologies and dynamics within the sources, and we measure an average Hα velocity dispersion of &lt;σ&gt; = 220 ± 80 km s<SUP>-1</SUP> and an average half-light radius of &lt;r<SUB>1/2</SUB>&gt; = 3.7 ± 0.8 kpc. The dynamical measure, &lt;V<SUB>obs</SUB>/2σ&gt; = 0.9 ± 0.1, for the SMGs is higher than in more quiescent star-forming galaxies at the same redshift, highlighting a difference in the dynamics of the two populations. The far-infrared star formation rates (SFRs) of the SMGs, measured using Herschel-SPIRE† far-infrared photometry, are on average 370 ± 90 M<SUB>☉</SUB> yr<SUP>-1</SUP>, which is ̃2 times higher than the extinction-corrected SFRs of the more quiescent star-forming galaxies. Six of the SMGs in our sample show strong evidence for kinematically distinct multiple components with average velocity offsets of 200 ± 100 km s<SUP>-1</SUP> and average projected spatial offsets of 8 ± 2 kpc, which we attribute to systems in the early stages of major mergers. Indeed, all SMGs are classified as mergers from a kinemetry analysis of the velocity and dispersion field asymmetry. We bring together our sample with the seven other SMGs with integral field unit observations to describe the ionized gas morphologies and kinematics in a sample of 16 SMGs. By comparing the velocity and spatial offsets of the SMG Hα components with subhalo offsets in the Millennium Simulation data base, we infer an average halo mass for SMGs in the range of 13 &lt; log (M[h<SUP>-1</SUP> M<SUB>☉</SUB>]) &lt; 14. Finally, we explore the relationship between the velocity dispersion and star formation intensity within the SMGs, finding that the gas motions are consistent with the Kennicutt-Schmidt law and a range of extinction corrections, although they might also be driven by the tidal torques from merging or even the star formation itself....

    DOI: 10.1111/j.1365-2966.2012.21386.x

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  110. 日本天文学会 早川幸男基金による渡航報告書 : AOGS2011-8th Annual Meeting and Geosciences World Community Exhibition-

    梅畑 豪紀

    天文月報   Vol. 105 ( 2 ) page: 112   2012.1

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  111. OBSERVATIONS OF THE NEAR-TO MID-INFRARED UNIDENTIFIED EMISSION BANDS IN THE INTERSTELLAR MEDIUM OF THE LARGE MAGELLANIC CLOUD

    Tamami I. Mori, Itsuki Sakon, Takashi Onaka, Hidehiro Kaneda, Hideki Umehata, Ryou Ohsawa

    ASTROPHYSICAL JOURNAL   Vol. 744 ( 1 )   2012.1

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    We present the results of near-tomid-infrared slit spectroscopic observations (2.55-13.4 mu m) of the diffuse emission toward nine positions in the Large Magellanic Cloud with the infrared camera on board AKARI. The target positions are selected to cover a wide range of the intensity of the incident radiation field. The unidentified infrared bands at 3.3, 6.2, 7.7, 8.6, and 11.3 mu m are detected toward all the targets and ionized gas signatures; hydrogen recombination lines and ionic forbidden lines are detected toward three of them. We classify the targets into two groups: those without the ionized gas signatures (Group A) and those with the ionized signatures (Group B). Group A includes molecular clouds and photodissociation regions, whereas Group B consists of H II regions. In Group A, the band ratios of I-3.3 (mu m)/I-11.3 (mu m), I-6.2 (mu m)/I-11.3 (mu m), I-7.7 (mu m)/I-11.3 (mu m), and I-8.6 (mu m)/I-11.3 (mu m) show positive correlation with the IRAS and AKARI colors, but those of Group B do not follow the correlation. We discuss the results in terms of the polycyclic aromatic hydrocarbon (PAH) model and attribute the difference to the destruction of small PAHs and an increase in the recombination due to the high electron density in Group B. In the present study, the 3.3 mu m band provides crucial information on the size distribution and/or the excitation conditions of PAHs and plays a key role in the distinction of Group A from B. The results suggest the possibility of the diagram of I-3.3 (mu m)/I-11.3 (mu m) versus I-7.7 (mu m)/I-11.3 (mu m) as an efficient diagnostic tool to infer the physical conditions of the interstellar medium.

    DOI: 10.1088/0004-637X/744/1/68

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  112. DIFFUSE INTERSTELLAR PAH EMISSION IN THE LMC OBSERVED WITH THE AKARI/IRC

    H. Umehata, I. Sakon, T. Onaka, D. Kato

    ADVANCES IN GEOSCIENCES, VOL 30: PLANETARY SCIENCE (PS) AND SOLAR & TERRESTRIAL SCIENCE (ST)     page: 15 - 23   2012

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    We present the results of mid-infrared (MIR) slit spectroscopic observations of the diffuse interstellar medium (ISM) in the Large Magellanic Cloud (LMC) with the Infrared Camera (IRC) onboard AKARI. We have observed seven slit points across the whole galaxy, which have the (CO)-C-12 (J = 1 -0) detection by NANTEN survey, and detect distinct unidentified infrared (UIR) bands (6.2 mu m, 7.7 mu m, 8.6 mu m, 11.2 mu m) for six points, while there are no signature of UIR bands in the spectra of one points. The comparison between the intensity ratios of 7.7 mu m/11.2 mu m and the IRAS 60 mu m/100 mu m color are carried out. We find that the band ratios peak at positions with an intermediate IRAS 60 mu m/100 mu m color of I-60 mu m/I-100 mu m similar to 0.5 and decreases at positions with lower or higher IRAS 60 mu m/100 mu m colors of I-60 mu m/I-100 mu m similar to 0.4 and I-60 mu m/I-100 mu m similar to 0.6-0.7, respectively. This result indicates the transition of the ionization state of PAHs relying on the gas phase and radiation environment.

    DOI: 10.1142/9789814405744_0002

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  113. Diagnosis of PAH Properties and ISM Conditions based on the Near-Infrared and Mid-Infrared UIR Bands

    T. I. Mori, I. Sakon, T. Onaka, H. Kaneda, H. Umehata, R. Ohsawa

    GALACTIC ARCHAEOLOGY: NEAR-FIELD COSMOLOGY AND THE FORMATION OF THE MILKY WAY   Vol. 458   page: 133 - +   2012

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    We report the results of near-infrared (NIR) to mid-infrared (MIR) slit spectroscopic observations of the diffuse emission from the Large Magellanic Cloud (LMC) with the Infrared Camera (IRC) on board AKARI. The present results suggest that the 3.3 mu m Unidentified Infrared (UIR) band provides powerful information on the size distribution and/or the excitation conditions of PAHs. A combination of the MIR bands with the 3.3 mu m band, such as the diagram of I-3.3/I-11.3 vs. I-7.7/I-11.3, is shown to be a useful diagnostic tool for the radiation conditions of the PAH emitting regions.

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  114. DIFFUSE INTERSTELLAR PAH EMISSION IN THE LMC OBSERVED WITH THE AKARI/IRC

    Umehata H., Sakon I., Onaka T., Kato D.

    ADVANCES IN GEOSCIENCES, VOL 30: PLANETARY SCIENCE (PS) AND SOLAR & TERRESTRIAL SCIENCE (ST)     page: 15 - 23   2012

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Books 7

  1. ALMA2Project-ALMAが切り拓く2020年代の科学のフロンティア

    梅畑豪紀( Role: Contributor ,  第3章「アルマ望遠鏡によるこれまでの研究成果」、第4章「アルマ2プロジェクトの科学的展望」)

    国立天文台  2019 

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  2. パリティ2017年1月号

    梅畑豪紀( Role: Contributor ,  ALMAでみえてきた爆発的星形成銀河と宇宙大規模構造の相関)

    丸善出版  2017 

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  3. 天文月報2016年7月号

    ( Role: Contributor ,  日本天文学会 早川幸男基金による渡航報告書 「In the footsteps of galaxies: Tracing the Evolution of Environmental Ef¬fects)

    日本天文学会  2016.7 

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  4. 東京大学大学院理学系研究科・理学部ニュース

    梅畑豪紀( Role: Contributor ,  115億光年かなたの宇宙で見つかった怪物銀河の大集団)

    東京大学大学院理学系研究科・理学部  2016.3 

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  5. 天文月報2013年12月号

    梅畑豪紀( Role: Contributor ,  日本天文学会 早川幸男基金による渡航報告書 IRAM観測)

    日本天文学会  2013.12 

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  6. 天文月報2013年1月号

    梅畑豪紀(日本天文学会 早川幸男基金による渡航報告書 39th COSPAR Scientific Assembly)

    日本天文学会  2013.1 

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  7. 天文月報2012年2月号

    梅畑豪紀(早川幸男基金による渡航報告書 AOGS2011 -8th Annual Meeting and Geosciences World Community Exhibition-)

    日本天文学会  2012.2 

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MISC 15

  1. ALMAによるz=8.31のライマンブレイク銀河の300pc分解能撮像

    田村陽一, BAKX Tom, 今村千博, 萩本将都, 竹内努, 井上昭雄, 徳岡剛史, 橋本拓也, 松尾宏, 馬渡健, 松田有一, LEE Minju, 梅畑豪紀, 吉田直紀, 森脇可奈, 廿日出文洋, 河野孝太郎, 岡本崇, ZACKRISSON E., BINGGELI C., 太田一陽, 澁谷隆俊, 清水一紘, 谷口義明

    日本天文学会年会講演予稿集   Vol. 2022   2022

  2. z=7クエーサーにおける大規模アウトフローと始原的共進化関係

    泉拓磨, 今西昌俊, 馬場俊介, 中西康一郎, 松岡良樹, 長尾透, 藤本征史, 尾上匡房, STRAUSS Michael A., 梅畑豪紀, 河野孝太郎, SILVERMAN John D., 柏川伸成, 川口俊弘

    日本天文学会年会講演予稿集   Vol. 2021   2021

  3. HI Tomograpic survey in the SSA22 field (SSASS-HIT) (II): tomographic map at 2.7<z<3.55

    馬渡健, 井上昭雄, 山田亨, 大塚拓也, 林野友紀, 山中郷史, 菅原悠馬, LEE Khee-Gan, TEJOS Nicolas, SCHLEGEL David, PROCHASKA Xavier, 柏川伸成, 松田有一, 岩田生, HENNAWEI Josep, 梅畑豪紀, 田村陽一, 向江志郎, 大内正巳

    日本天文学会年会講演予稿集   Vol. 2021   2021

  4. 大質量銀河団SPT-CL J0615-5746に属するCO分子輝線銀河が示す環境効果による星形成活動の抑制

    中野覚矢, 田村陽一, 谷口暁星, 萩本将都, 竹内努, BAKX T., 井上昭雄, 橋本拓也, 松尾宏, 梅畑豪紀, SALMON B., COE D., BRADLEY L., OESCH P., STRAIT V., BRADAC M.

    日本天文学会年会講演予稿集   Vol. 2021   2021

  5. 原始銀河団領域SSA22におけるJVLA5cm電波連続光観測:I.ソースカタログの作成

    松田慧一, 梅畑豪紀, 田村陽一, 谷口暁星, BAKX T., 河野孝太郎, 中西康一郎, 但木謙一, RUJOPAKARN W., IVISON R., AO Y., YUN M. S.

    日本天文学会年会講演予稿集   Vol. 2021   2021

  6. Large Submillimeter Telescope (LST): 5

    河野孝太郎, 廿日出文洋, 竹腰達哉, 江草芙実, 田村陽一, 谷口暁星, 井上昭雄, 川邊良平, 大島泰, 石井峻, 遠藤光, 唐津謙一, 梅畑豪紀, 濤崎智佳

    日本天文学会年会講演予稿集   Vol. 2020   2020

  7. Importance of Dust in the Evolution of Galaxies: Prospect for SPICA

    竹内努, 泉拓磨, 今西昌俊, 久保真理子, 播金優一, 馬場俊介, 山下拓時, 田村陽一, 梅畑豪紀, 鳥羽儀樹, 長峯健太郎, 橋本拓也, 市川幸平, 和田武彦

    日本天文学会年会講演予稿集   Vol. 2020   2020

  8. ALMA Reveals an Extremely Compact Submillimeter Galaxy in the Early Universe

    小山紗桜, 伊王野大介, 但木謙一, 泉拓磨, 川邊良平, 松田有一, 中西康一郎, 植田準子, 道山知成, 安藤未彩希, YUN M.S., WILSON G. W., ARETXAGA I., HUGHES D., 廿日出文洋, 河野孝太郎, 五十嵐創, 李民主, 田村陽一, 斉藤俊貴, 梅畑豪紀

    日本天文学会年会講演予稿集   Vol. 2019   2019

  9. ASTE搭載用多色連続波カメラの開発:(15)科学データ解析

    泉奈都子, 大島泰, 竹腰達哉, 大田原一成, 石井峻, 荒井均, 廣田晶彦, 南谷哲宏, 岩下浩幸, 前川淳, 上水和典, 伊藤哲也, 藤井泰範, 斎藤智樹, 宮本祐介, 金子紘之, 諸隈佳菜, 松尾宏, 川邊良平, 山口正行, 泉拓磨, 谷口暁星, 梅畑豪紀, LEE Minju, 山口裕貴, 安藤亮, 石田剛, 田村陽一, 河野孝太郎, 中坪俊一, 森章一, 香内晃, 徂徠和夫, 鈴木駿汰, 村岡和幸, 濤崎智佳, 小麥真也

    日本天文学会年会講演予稿集   Vol. 2017   page: 214   2017.2

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  10. ASTE搭載用多色連続波カメラの開発:(12)プロジェクト進捗

    大島泰, 竹腰達哉, 大田原一成, 泉奈都子, 石井峻, 荒井均, 廣田晶彦, 南谷哲宏, 岩下浩幸, 前川淳, 上水和典, 伊藤哲也, 藤井泰範, 斎藤智樹, 宮本祐介, 金子紘之, 諸隈佳菜, 松尾宏, 川邊良平, 山口正行, 泉拓磨, 谷口暁星, 梅畑豪紀, LEE Minju, 山口裕貴, 安藤亮, 石田剛, 田村陽一, 河野孝太郎, 中坪俊一, 森章一, 香内晃, 徂徠和夫, 鈴木駿汰, 村岡和幸, 濤崎智佳, 小麥真也

    日本天文学会年会講演予稿集   Vol. 2017   page: 213   2017.2

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  11. ASTE搭載用多色連続波カメラの開発:(13)光学系の評価

    竹腰達哉, 大島泰, 大田原一成, 泉奈都子, 石井峻, 荒井均, 廣田晶彦, 南谷哲宏, 岩下浩幸, 前川淳, 上水和典, 伊藤哲也, 藤井泰範, 斎藤智樹, 宮本祐介, 金子紘之, 諸隈佳菜, 松尾宏, 川邊良平, 山口正行, 泉拓磨, 谷口暁星, 梅畑豪紀, LEE Minju, 山口裕貴, 安藤亮, 石田剛, 田村陽一, 河野孝太郎, 中坪俊一, 森章一, 香内晃, 徂徠和夫, 鈴木駿汰, 村岡和幸, 濤崎智佳, 小麥真也

    日本天文学会年会講演予稿集   Vol. 2017   page: 213   2017.2

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  12. ASTE搭載用多色連続波カメラの開発:(6)科学評価活動

    田村陽一, 大島泰, 竹腰達哉, 大田原一成, 川邊良平, 泉奈都子, 斎藤智樹, 浅山信一郎, 奥田武志, 鎌崎剛, 芦田川京子, 松居隆之, 前川淳, 荒井均, 廣田晶彦, 松尾宏, 南谷哲宏, 宮本祐介, 金子紘之, 諸隈佳菜, 石井峻, 河野孝太郎, 泉拓磨, 谷口暁星, 梅畑豪紀, LEE Minju, 山口裕貴, 安藤亮, 山口正行, 石田剛, 村岡和幸, 鈴木駿汰, 濤崎智佳, 小麥真也

    日本天文学会年会講演予稿集   Vol. 2016   page: 206   2016.8

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  13. 学部生に伝える研究最前線

    関根 康人, 伊藤 恭子, 福田 裕穂, 梅畑 豪紀, 田村 陽一, 河野 孝太郎

    東京大学理学系研究科・理学部ニュース   Vol. 47 ( 6 ) page: 12 - 14   2016.3

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    Language:Japanese   Publisher:東京大学大学院理学系研究科・理学部  

    土星の衛星エンセラダスに生命を育む海がある!?/自己抑制の仕組みでバランスを保つ植物の根/115億光年かなたの宇宙で見つかった怪物銀河の大集団

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  14. 超広帯域ミリ波サブミリ波観測に基づく大規模構造の進化の研究:進捗状況

    河野孝太郎, 酒井剛, 田村陽一, 五十嵐創, 梅畑豪紀, 泉拓磨, 川辺良平, 大島泰, 廣田晶彦, 佐藤立博, 岩下浩幸, 久野成夫, 江澤元, 伊王野大介, 児玉忠恭, 松原英雄, 南谷哲宏, 竹腰達哉, 中島拓, 廿日出文洋

    日本天文学会年会講演予稿集   Vol. 2013   2013

  15. An ultra bright SMG behind a nearby cluster

    梅畑豪紀, 河野孝太郎, 田村陽一, 五十嵐創, 鈴木賢太, 大島泰, 田中壱, 川邊良平, 伊王野大介, 中西康一郎, 江上英一, 廿日出文洋

    日本天文学会年会講演予稿集   Vol. 2012   2012

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Presentations 69

  1. Charting galaxy formation within cosmic web filaments

    Hideki Umehata

    2024.2.6 

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  2. ALMA-MUSE-JWST-Chandra Deep Field in a proto-cluster

    Hideki Umehata

    the ALMA science workshop between Chile and Japan  2023.12.12 

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  3. Accelerated massive galaxy formation along the cosmic web filaments at z=3

    Hideki Umehata

    ALMA at 10 years: Past, Present, and Future  2023.12.4 

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  4. Resolved perspectives on the formation of massive galaxies in the cosmic web filaments at a redshift of z=3

    Hideki Umehata

    Resolving the Extragalactic Universe with ALMA & JWST  2023.11.6 

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    Event date: 2023.11

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  5. Massive galaxy formation along the cosmic web filaments at z=3 Invited

    Hideki Umehata

    First structures 2023 workshop  2023.9.7 

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    Event date: 2023.9

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  6. Obscured Phase of Co-evolution in a z=3 proto-cluster core

    Hideki Umehata

    AGN mini-WS  2023.6.26 

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  7. ngVLAによる原始銀河団探査 Invited

    梅畑豪紀

    ngVLA合同サイエンスワーキンググループ  2023.3.29 

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    Event date: 2023.3

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  8. 赤方偏移3の原始銀河団SSA22における銀河形成研究の今と今後

    梅畑豪紀

    2022年度 宇宙電波懇談会シンポジウム「2030年代の電波天文学」  2023.3.27 

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  9. Cosmic web filaments and galaxy evolution

    梅畑豪紀

    第30回YLCセミナー  2023.3.3 

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    Event date: 2023.3

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  10. Massive galaxy formation fed by cosmic web filaments at z=3

    Hideki Umehata

    A half century of mm/submm astronomy  2022.12.15 

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    Event date: 2022.12

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  11. Growth of galaxies and supermassive black holes in the cosmic web filaments at z = 3

    Hideki Umehata

    What Drives the Growth of Black Holes? A decade of Reflection  2022.9.28 

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    Event date: 2022.9

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  12. Molecular gas reservoirs within the cosmic web filaments at z=3

    梅畑豪紀

    日本天文学会秋季年会  2022.9.14 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  13. Galaxy growth within the cosmic web in a z=3 proto-cluster

    梅畑豪紀

    第136回宇宙進化研究センター談話会  2022.5.26 

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    Event date: 2022.5

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  14. Accelerated growth of galaxies and super-massive black holes within the cosmic web gas filaments at z=3

    Hideki Umehata

    Cosmic Cartography 2022  2022.3.8 

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    Event date: 2022.3

    Language:English   Presentation type:Oral presentation (general)  

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  15. Widely distributed cold gas and dust within a z=3 giant Lyα blob

    梅畑豪紀

    日本天文学会春季年会  2022.3.3 

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    Event date: 2022.3

    Language:Japanese   Presentation type:Oral presentation (general)  

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  16. Galaxy formation in a proto-cluster at z=3.1

    梅畑豪紀

    r-EMU Workshop 2021  2021.10.18 

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    Event date: 2021.10

    Language:English   Presentation type:Oral presentation (general)  

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  17. Review: IGM observation Invited

    Hideki Umehata

    Galaxy-IGM workshop 2021  2021.8.17 

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    Event date: 2021.8

    Language:Japanese   Presentation type:Oral presentation (keynote)  

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  18. Galaxy growth within the cosmic web in a proto-cluster

    Hideki Umehata

    2021.7.6 

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    Event date: 2021.7

    Language:English  

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  19. ALMAによる原始銀河団探査の現在地と更なる⾼感度観測への期待 Invited

    梅畑豪紀

    宇宙電波懇談会シンポジウム2020  2020.12.22 

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    Event date: 2020.12

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  20. Galaxy formation and evolution seen by ALMA and Subaru Invited

    Hideki Umehata

    2020.3.19 

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    Event date: 2020.3

    Language:English   Presentation type:Oral presentation (invited, special)  

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  21. 赤方偏移3の宇宙網における銀河形成研究の現在地

    梅畑豪紀

    つくば宇宙フォーラム  2019.12.11 

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    Event date: 2019.12

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  22. Gas filaments connecting galaxies and supermassive black holes in a proto-cluster

    Hideki Umehata

    SUBARU TELESCOPE 20TH ANNIVERSARY– Optical & Infrared Astronomy for the Next Decade –  2019.11.19 

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    Event date: 2019.11

    Language:English   Presentation type:Oral presentation (general)  

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  23. Proto-cluster survey with SPICA

    Hideki Umehata

    2019.11.8 

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    Event date: 2019.11

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  24. Gas filaments at z=3 revealed by MUSE

    Hideki Umehata

    2019.10.29 

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    Event date: 2019.10

    Language:Japanese   Presentation type:Oral presentation (general)  

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  25. ALMA Deep Field in the SSA22 proto-cluster at z=3

    Umehata, Hideki

    ALMA2019: Science Results and Cross-Facility Synergies  2019.10.14 

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    Event date: 2019.10

    Language:English   Presentation type:Poster presentation  

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  26. ngVLA and galaxy formation in proto-clusters Invited

    Umehata, Hideki

    ngVLA Workshop  2019.9.18 

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    Event date: 2019.9

    Language:English   Presentation type:Oral presentation (invited, special)  

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  27. Active dust-obscured star-formation at a z=3 proto-cluster

    Hideki Umehata

    IAU Symposium 352: Uncovering early galaxy evolution in the ALMA and JWST era  2019.6.6 

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    Event date: 2019.6

    Language:English   Presentation type:Oral presentation (general)  

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  28. ALMA Observations of LABs Invited

    Hideki Umehata

    Cosmic Shadow 2018  2018.11.23 

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    Event date: 2018.11

    Language:English   Presentation type:Oral presentation (invited, special)  

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  29. サブミリ波銀河探査の今後

    梅畑豪紀

    第二回若手銀河研究会  2018.11.22 

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    Event date: 2018.11

    Language:Japanese   Presentation type:Oral presentation (general)  

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  30. Massive Galaxy Formation at a z=3 proto-cluster revealed by ALMA and Subaru

    Hideki Umehata

    Subaru Seminar  2018.9.11 

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    Event date: 2018.9

    Language:English   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  31. ALMA deep survey in a z=3 proto-cluster field

    Hideki Umehata

    IAU General Assembly: Build-up of Galaxy Clusters  2018.8.23 

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    Event date: 2018.8

    Language:English   Presentation type:Oral presentation (general)  

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  32. Dusty star-forming galaxies at a high redshift proto-cluster

    Hideki Umehata

    2018.7.27 

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    Event date: 2018.7

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  33. Massive galaxies and surrounding matters at a z=3 proto-cluster

    Hideki Umehata

    2018.7.20 

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    Event date: 2018.7

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  34. Dusty star-forming galaxies at a high redshift proto-cluster

    Hideki Umehata

    2018.7.2 

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    Event date: 2018.7

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  35. ALMA Deep Field in SSA22

    Hideki Umehata

    SMG20 - Twenty years of Submillimetre Galaxies: STAR-FORMING GALAXIES AT HIGH REDSHIFTS  2017.8.1 

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    Event date: 2017.7 - 2017.8

    Language:English   Presentation type:Oral presentation (general)  

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  36. ADF22: ALMA Deep Field in SSA22

    Hideki Umehata

    The Galaxy Ecosystem. Flow of Baryons Through Galaxies  2017.7.24 

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    Event date: 2017.7

    Language:English   Presentation type:Poster presentation  

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  37. Extended Lyα emission around SMGs

    Hideki Umehata

    What Matter(s) Around Galaxies  2017.6.21 

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    Event date: 2017.6

    Language:English   Presentation type:Oral presentation (general)  

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  38. An extremely rich group of starbursts and AGNs at a z=3.1 proto-cluster core

    Hideki Umehata

    Galaxy evolution across time  2017.6.15 

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    Event date: 2017.6

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  39. ADF22: ALMA Deep Field in SSA22 Invited

    Hideki Umehata

    A workshop on ALMA deep surveys and their synergies with HST and JWST  2017.3.31 

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    Event date: 2017.3 - 2017.4

    Language:English   Presentation type:Oral presentation (invited, special)  

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  40. ALMA Reveals Strong [CII] Emission in a Galaxy Embedded in a Giant Lyman-α Blob at z=3.1

    Hideki Umehata

    The Snowbird Cosmic Lyman-Alpha Workshop (SnowCLAW)  2017.3.21 

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    Event date: 2017.3

    Language:English   Presentation type:Oral presentation (general)  

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  41. ADF22: ALMA Deep Field in SSA22

    Hideki Umehata

    ALMA/45m/ASTE Users Meeting 2016  2016.12.19 

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    Event date: 2016.12

    Language:English   Presentation type:Poster presentation  

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  42. ALMA Deep Field in SSA22

    Hideki Umehata

    Half a Decade of ALMA: Cosmic Dawns Transformed  2016.9.20 

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    Event date: 2016.9

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  43. ALMA Deep Field in SSA22: The survey description and source catalogue

    梅畑豪紀, 田村陽一, 河野孝太郎, 廿日出文洋, ADF22team

    2016年日本天文学会秋季年会  2016.9.15 

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    Event date: 2016.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  44. ALMA Deep Field in SSA22 Invited

    Hideki Umehata

    ALMA deep surveys on GOODS-S and beyond  2015.12.15 

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    Event date: 2015.12

    Language:English   Presentation type:Oral presentation (invited, special)  

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  45. Submillimeter Galaxies and PFS Invited

    Hideki Umehata

    PFS-SSP GALAXY SURVEY WORKSHOP 2015  2015.11.13 

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    Event date: 2015.11

    Language:English   Presentation type:Oral presentation (invited, special)  

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  46. Concentration of dusty starbursts and AGNs at a z=3.09 proto-cluster core

    Hideki Umehata

    In the footsteps of galaxies: tracing the evolution of environmental effect  2015.9.9 

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    Event date: 2015.9

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  47. Dusty Starbursts within a z=3 Large Scale Structure revealed by ALMA

    Hideki Umehata

    XXIX IAU General Assembly: ‘IAUS 319: Galaxies at High Redshift and Their Evolution over Cosmic Time  2015.8.10 

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    Event date: 2015.8

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  48. Dusty Starbursts and AGNs in a z=3.1 Protocluster revealed by ALMA

    Hideki Umehata

    Theoretical and Observational Progress on Large-scale Structure of the Universe  2015.7.20 

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    Event date: 2015.7

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  49. Dusty Starbursts within a z=3 Large Scale Structure revealed by ALMA

    Hideki Umehata

    Gas, Dust, and Star-Formation in Galaxies from the Local to Far Universe 2015  2015.5.25 

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    Event date: 2015.5

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  50. Dusty Starbursts within a z=3 Large Scale Structure

    Hideki Umehata

    The ALMA science conference: ‘Revolution in Astronomy with ALMA - the 3rd year -  2014.12.8 

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    Event date: 2014.12

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  51. Dusty Starbursts within a z=3 Large Scale Structure

    Hideki Umehata

    Transformational Science in the ALMA Era: Multi-Wavelength Studies of Galaxy Evolution  2014.8.4 

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    Event date: 2014.8

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  52. The Picture of Submillimeter Galaxies in a Proto-cluster

    H. Umehata, Y. Tamura, K. Kohno, S. Ikarashi, K. nakanishi, D. Iono, B. Hatsukade

    NRO Users meeting  2014.7.23 

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    Event date: 2014.7

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  53. SSA22領域におけるサブミリ波銀河の性質:IV. PdBIによるサブミリ波高分解能観測

    梅畑豪紀, 田村陽一, 五十嵐創, 河野孝太郎, 中西康一郎, 高田唯史, 川邊良平, 伊王野大介, 松田有一, 廿日出文洋, 山田亨, 久保真理子

    日本天文学会秋季年会  2013.9.11 

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    Event date: 2013.9

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  54. ADF22: ALMA Deep Field in SSA22

    H. UMEHATA, Y.Tamura, K.Kohno, K.Suzuki, S.Ikarashi, K.Nakanishi, D.Iono, B.Hatsukade

    ALMA時代の宇宙構造形成理論兼初代星初代銀河研究会  2013.1.25 

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  55. Submillimeter Galaxies in the SSA22 Protocluster at z = 3.1

    Hideki Umehata

    New Trends in Radio Astronomy in the ALMA Era,  2012.12.3 

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    Event date: 2012.12

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  56. An ultra bright SMG behind a nearby cluster

    梅畑豪紀, 河野孝太郎, 田村陽一, 五十嵐創, 鈴木賢太, 大島泰, 田中壱, 川邊良平, 伊王野大介, 中西康一郎, 江上英一, 廿日出文洋

    日本天文学会秋季年会  2012.9.19 

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    Event date: 2012.9

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  57. Submillimeter Galaxies in the SSA22 Protocluster at z=3.1

    Hideki Umehata

    Growing-up at high redshift: from proto-clusters to galaxy clusters  2012.9.11 

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    Event date: 2012.9

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  58. The Picture of Submillimeter Galaxies in the SSA22 Protocluster

    H. Umehata, Y.Tamura, K.Kohno, K.Suzuki, S.Ikarashi, K.Nakanishi, D.Iono, B.Hatsukade

    野辺山ユーザーズミーティング  2012.7.25 

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    Event date: 2012.7

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  59. The Picture of Submillimeter Galaxies in the SSA22 Proto-cluster region

    Hideki Umehata

    The 38th COSPAR Scientific Assembly  2012.7.16 

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  60. SSA22 領域におけるサブミリ波銀河の性質:III. 大規模構造との関係性

    梅畑豪紀, 田村陽一, 五十嵐創, 鈴木健太, 河野孝太郎, 中西康一郎, 高田唯史, 川邊良平, 伊王野大介, 廿日出文洋, 山田亨, 林野友紀, 市川隆, 内一由夏, 久保真理子, 松田有一

    日本天文学会春季年会  2012.3.19 

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    Event date: 2012.3

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  61. 原始銀河団SSA22におけるサブミリ波銀河の性質とSPICAへの期待

    梅畑豪紀

    次世代赤外線天文衛星SPICAが目指す宇宙星形成史とブラックホール進化の解明  2011.10.19 

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    Event date: 2011.10

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  62. SSA22 領域におけるサブミリ波銀河の性質:II. 赤方偏移の推定

    梅畑豪紀, 田村陽一, 五十嵐創, 鈴木健太, 河野孝太郎, 中西康一郎, 高田唯史, 川邊良平, 伊王野大介, 廿日出文洋, 山田亨, 林野友紀, 市川隆, 内一由夏, 久保真理子, 松田有一

    日本天文学会秋季年会  2011.9.20 

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    Event date: 2011.9

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  63. AzTEC/ASTE 1.1mm SMGs survey of the SSA22:Identification and photometric redshift calcuration

    H. Umehata, Y. Tamura, K. Kohno, S. Ikarashi, K. Suzuki, K. Nakanishi, T. Takata, R. Kwabe, D. Iono, B. Hastukade, T. Yamada, Y. Hayashino, T. Ichikawa, Y. Uchimoto, M. Kubo, Y. Matsuda

    Large Aperture Millimeter/Submillimeter Telescopes in the ALMA Era  2011.9.12 

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    Event date: 2011.9

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  64. Diffuse interstellar PAH emission in the LMC observed with the AKARI/IRC

    Hideki Umehata

    Annual Meeting of Asia Oceania Geosciendce Society (AOGS2011)  2011.8.8 

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    Event date: 2011.8

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  65. SSA22 領域におけるサブミリ波銀河の性質:I. 多波長同定

    梅畑豪紀, 五十嵐創, 鈴木健太, 河野孝太郎, 中西康一郎, 高田唯史, 川邊良平, 廿日出文洋, 伊王野大介, 田村陽一

    天文学会春季年会  2011.3.17 

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  66. SMA observations of RXJ2228

    Hideki Umehata

    The NRO Workshop  2011.1.21 

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  67. AzTEC/ASTE 1.1 mm Survey of the SSA22 Protocluster Field: II. Source Identification

    梅畑豪紀

    ALMA User’s Meeting 2010  2010.12 

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    Event date: 2010.12

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  68. Diffuse interstellar PAH emission in the LMC observed with the AKARI/IRC

    Hideki Umehata

    The 5th Zermatt ISM Symposium  2010.9.20 

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  69. あかりによる大マゼラン星雲のダストの赤外線分光観測

    梅畑豪紀, 左近樹, 加藤大輔, 尾中敬

    日本天文学会春季年会  2010.3 

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▼display all

Research Project for Joint Research, Competitive Funding, etc. 1

  1. Charting galaxy formation within the cosmic web

    2024.4 - 2027.3

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    Authorship:Principal investigator 

KAKENHI (Grants-in-Aid for Scientific Research) 5

  1. Co-evolution of cosmic web filaments and galaxies in the early universe

    Grant number:22KK0231  2022

    Grants-in-Aid for Scientific Research  Fund for the Promotion of Joint International Research (Fostering Joint International Research (A))

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    Authorship:Principal investigator 

    Grant amount:\15080000 ( Direct Cost: \11600000 、 Indirect Cost:\3480000 )

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  2. Gaseous network connecting galaxies in the early Universe

    Grant number:20H01953  2020.4 - 2025.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

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    Authorship:Principal investigator 

    Grant amount:\15340000 ( Direct Cost: \11800000 、 Indirect Cost:\3540000 )

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  3. Interaction between galaxies and intergalactic medium uncovered by IFU and ALMA

    Grant number:17K14252  2017.4 - 2020.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)  Grant-in-Aid for Young Scientists (B)

    Umehata Hideki

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    Authorship:Principal investigator 

    Grant amount:\4030000 ( Direct Cost: \3100000 、 Indirect Cost:\930000 )

    In this work, our purpose was to uncover gaseous network, so called cosmic web, using Lyman-alpha emission as a probe, and to investigate the relation between cosmic web and galaxies. We carried out observations using VLT/MUSE, which is a sensitive optical integral field unit with a large format in FY2017 and FY 2018. ALMA was also utilized to investigate ISMs in galaxies. Finally we published a paper in Science in 2019 to report the first identification of cosmic web filaments connecting a number of galaxies and super-massive black holes. International press release was made, too.

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  4. 原始銀河団における爆発的星形成活動の起源と進化の解明

    Grant number:16H06713  2016.8 - 2018.3

    日本学術振興会  科学研究費助成事業 研究活動スタート支援  研究活動スタート支援

    梅畑 豪紀

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    Authorship:Principal investigator 

    Grant amount:\2990000 ( Direct Cost: \2300000 、 Indirect Cost:\690000 )

    本研究の目的は、宇宙の星形成活動の最盛期(赤方偏移3付近)において、銀河形成の環境依存性を明らかにすることである。この時代の宇宙には多数の銀河が群れ集まっている、原始銀河団と呼ばれる場所が存在し、当時の銀河形成、星形成活動の主要な場であったと考えられている。しかし、中でも最も活発に星形成を行う銀河種族(爆発的星形成銀河、あるいはサブミリ波銀河)は大量の塵によって星からの光が隠されてしまい、可視光や近赤外線ではその姿を捉えることができていなかった。本研究ではこれら「隠された」銀河種族の理解を追求している。
    <BR>
    本研究では赤方偏移3.1の原始銀河団SSA22の中心部の探査を推進した。この時代において最も高密度な環境であり、銀河形成と環境の関係を調べる上で最適の領域である。加えて、2015年に申請者によって極めて広く(7平方分)、深い、波長1.1mmの観測が実行されている。このようなアルマ深宇宙探査領域(アルマディープフィールド)は世界でも未だ数例しか実行されておらず、高密度環境を対象にしたものでは唯一のデータである。研究は非常に順調に推移した。申請者が筆頭提案者となって獲得したアルマ望遠鏡のデータの解析を精力的に進め、ターゲットとした原始銀河団におけるサブミリ波銀河を多数検出し、その分布や大きさ、星形成活動の活発さといった物理的性質の統計的な調査を進めることができた。得られた成果に基づき、筆頭著者として査読論文を2本出版し、4件の国際会議における研究発表を行った(招待講演1件を含む)。

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  5. サブミリ波観測で探る爆発的星形成銀河及び大質量ブラックホールの形成環境

    Grant number:14J11481  2014.4 - 2016.3

    日本学術振興会  科学研究費助成事業 特別研究員奨励費  特別研究員奨励費

    梅畑 豪紀

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    Authorship:Principal investigator 

    Grant amount:\2370000 ( Direct Cost: \2100000 、 Indirect Cost:\270000 )

    宇宙で最も明るい天体種族にサブミリ波銀河とクエーサーがある。サブミリ波銀河とは爆発的な星形成を行っている銀河であり、生まれた大質量星が周囲の星間ダストを暖め、ダストからの熱放射が卓越する結果サブミリ波で明るく観測される。他方、母銀河の中心にある大質量ブラッククホールへの物質の降着で起きる重力エエネルギーの解放により輝く活動銀河核の中で、最もブラックホールの質量が大きく明るいものがクエーサーである。両者は赤方偏移 2-3(宇宙開闢から数えて約 33億歳-23億歳) の宇宙に多く発見されており、サブミリ波銀河の中には活動銀河核を持つものがあることなどから、サブミリ波銀河の一部は その後クエーサーへ進化すると考えられている。サブミリ波銀河やクエーサーの極めて高い活動性を引き起こす原因とされるのが銀河の衝突・合体であり、形態学的特徴や理論予測から支持されている。従ってその時代の宇宙で銀河数密度が最も高い場所、 原始銀河団がその形成環境として有力視される。また、サブミリ波銀河からクエーサーへ進化する途中の天体(原始クエーサー)を発見できれば一見違う性質を持つこの 2 つの銀河種族がどのように一つの進化 系列でつながるのかを解明できると期待される。本研究を通して、原始銀河団の中心部で確かにサブミリ波銀河が多く形成されていること、その多くがクエーサーへの進化途中にある可能性が高いことが示された。本研究成果は爆発的星形成活動と宇宙大規模構造を直接的に結びつける成果であり、論文として出版されるとともに広くプレスリリースされた。

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