2024/12/08 更新

写真a

マワタリ ケン
馬渡 健
所属
理工学術院 理工学術院総合研究所
職名
次席研究員(研究院講師)
学位
博士(理学) ( 東北大学 )

経歴

  • 2024年04月
    -
    継続中

    早稲田大学   理工学術院総合研究所   次席研究員(研究院講師)

  • 2023年04月
    -
    2024年03月

    筑波大学   数理物質系   研究員

  • 2021年04月
    -
    2023年03月

    国立天文台   ハワイ観測所   特任研究員

  • 2018年04月
    -
    2021年03月

    東京大学   宇宙線研究所   ICRR Fellow

  • 2015年04月
    -
    2018年03月

    大阪産業大学   デザイン工学部   博士研究員

  • 2013年04月
    -
    2015年03月

    日本学術振興会   特別研究員(DC2)

  • 2012年10月
    -
    2014年01月

    ハーバード・スミソニアン天文台

▼全件表示

学歴

  • 2010年04月
    -
    2015年03月

    東北大学   大学院理学研究科   天文学専攻  

  • 2006年04月
    -
    2010年03月

    東北大学   理学部   宇宙地球物理学科  

所属学協会

  •  
     
     

    日本天文学会

研究分野

  • 天文学

研究キーワード

  • 高赤方偏移

  • 銀河の形成・進化

  • 観測

  • 天文学

メディア報道

  • 頭脳循環プロジェクトニュースレター Vol. 4

    会誌・広報誌

    東北大学天文学専攻  

    2013年07月

 

論文

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

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

    Monthly Notices of the Royal Astronomical Society   534 ( 4 ) 3552 - 3564  2024年10月

     概要を見る

    ABSTRACT

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

    DOI

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

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

    Astrophysical Journal Letters   955 ( 1 )  2023年09月

     概要を見る

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

    DOI

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    14
    被引用数
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  • 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   953 ( 1 )  2023年08月

     概要を見る

    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.

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  • Cosmological-scale Ly & alpha; Forest Absorption around Galaxies and AGNs Probed with the HETDEX and SDSS Spectroscopic Data

    Dongsheng Sun, Ken Mawatari, Masami Ouchi, Yoshiaki Ono, Hidenobu Yajima, Yechi Zhang, Makito Abe, William P. Bowman, Erin Mentuch Cooper, Dustin Davis, Daniel J. Farrow, Karl Gebhardt, Gary J. Hill, Chenxu Liu, Donald P. Schneider

    ASTROPHYSICAL JOURNAL   951 ( 1 )  2023年07月

     概要を見る

    We present cosmological-scale three-dimensional neutral hydrogen (H i) tomographic maps at z = 2-3 over a total of 837 deg(2) in two blank fields that are developed with Ly & alpha; forest absorptions of 14,736 background Sloan Digital Sky Survey (SDSS) quasars at z = 2.08-3.67. Using the tomographic maps, we investigate the large-scale (& GSIM;10 h (-1) cMpc) average H i radial profiles and two-direction profiles of the line-of-sight (LOS) and transverse directions around galaxies and active galactic nuclei (AGNs) at z = 2-3 identified by the Hobby-Eberly Telescope Dark Energy eXperiment survey and SDSS, respectively. The peak of the H i radial profile around galaxies is lower than the one around AGNs, suggesting that the dark matter halos of galaxies are less massive on average than those of AGNs. The LOS profile of AGNs is narrower than the transverse profile, indicating the Kaiser effect. There exist weak absorption outskirts at & GSIM;30 h (-1) cMpc beyond H i structures of galaxies and AGNs found in the LOS profiles that can be explained by the H i gas at & GSIM;30 h (-1) cMpc falling toward the source position. Our findings indicate that the H i radial profile of AGNs has transitions from proximity zones (& LSIM;a few h (-1) cMpc) to the H i structures (& SIM;1-30 h (-1) cMpc) and the weak absorption outskirts (& GSIM;30 h (-1) cMpc). Although there is no significant dependence of AGN types (type 1 vs. type 2) on the H i profiles, the peaks of the radial profiles anticorrelate with AGN luminosities, suggesting that AGNs' ionization effects are stronger than the gas mass differences.

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

    Ken Mawatari, Akio K. Inoue, Toru Yamada, Tomoki Hayashino, J. Xavier Prochaska, Khee-Gan Lee, Nicolas Tejos, Nobunari Kashikawa, Takuya Otsuka, Satoshi Yamanaka, David J. Schlegel, Yuichi Matsuda, Joseph F. Hennawi, Ikuru Iwata, Hideki Umehata, Shiro Mukae, Masami Ouchi, Yuma Sugahara, Yoichi Tamura

    The Astronomical Journal    2023年05月

    DOI

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  • Detections of [C ii] 158 μm and [O iii] 88 μm in a Local Lyman Continuum Emitter, Mrk 54, and Its Implications to High-redshift ALMA Studies*

    Ryota Ura, Takuya Hashimoto, Akio K. Inoue, Dario Fadda, Matthew Hayes, Johannes Puschnig, Erik Zackrisson, Yoichi Tamura, Hiroshi Matsuo, Ken Mawatari, Yoshinobu Fudamoto, Masato Hagimoto, Nario Kuno, Yuma Sugahara, Satoshi Yamanaka, Tom J. L. C. Bakx, Yurina Nakazato, Mitsutaka Usui, Hidenobu Yajima, Naoki Yoshida

    ASTROPHYSICAL JOURNAL   948 ( 1 )  2023年05月

     概要を見る

    We present integral field, far-infrared (FIR) spectroscopy of Mrk 54, a local Lyman continuum emitter, obtained with FIFI-LS on the Stratospheric Observatory for Infrared Astronomy. This is only the second time, after Haro 11, that [C ii] 158 mu m and [O iii] 88 mu m spectroscopy of the known LCEs have been obtained. We find that Mrk 54 has a strong [C ii] emission that accounts for similar to 1% of the total FIR luminosity, whereas it has only moderate [O iii] emission, resulting in the low [O iii]/[C ii] luminosity ratio of 0.22 +/- 0.06. In order to investigate whether [O iii]/[C ii] is a useful tracer of f (esc) (LyC escape fraction), we examine the correlations of [O iii]/[C ii] and (i) the optical line ratio of O-32 equivalent to [O iii] 5007 angstrom/[O ii] 3727 angstrom, (ii) specific star formation rate, (iii) [O iii] 88 mu m/[O i] 63 mu m ratio, (iv) gas-phase metallicity, and (v) dust temperature based on a combined sample of Mrk 54 and the literature data from the Herschel Dwarf Galaxy Survey and the LITTLE THINGS Survey. We find that galaxies with high [O iii]/[C ii] luminosity ratios could be the result of high ionization (traced by O-32), bursty star formation, high ionized-to-neutral gas volume filling factors (traced by [O iii] 88 mu m/[O i] 63 mu m), and low gas-phase metallicities, which is in agreement with theoretical predictions. We present an empirical relation between the [O iii]/[C ii] ratio and f (esc) based on the combination of the [O iii]/[C ii] and O-32 correlation, and the known relation between O-32 and f (esc). The relation implies that high-redshift galaxies with high [O iii]/[C ii] ratios revealed by the Atacama Large Millimeter/submillimeter Array may have f (esc) greater than or similar to 0.1, significantly contributing to the cosmic reionization.

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    3
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  • A Comprehensive Study of Galaxies at z ∼ 9-16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch

    Yuichi Harikane, Masami Ouchi, Masamune Oguri, Yoshiaki Ono, Kimihiko Nakajima, Yuki Isobe, Hiroya Umeda, Ken Mawatari, Yechi Zhang

    Astrophysical Journal, Supplement Series   265 ( 1 )  2023年03月

     概要を見る

    We conduct a comprehensive study on dropout galaxy candidates at z ∼ 9-16 using the first 90 arcmin2 James Webb Space Telescope (JWST) Near Infrared Camera images taken by the early release observations (ERO) and early release science programs. With the JWST simulation images, we find that a number of foreground interlopers are selected with a weak photo-z determination (Δχ 2 > 4). We thus carefully apply a secure photo-z selection criterion (Δχ 2 > 9) and conventional color criteria with confirmations of the ERO Near Infrared Spectrograph spectroscopic redshifts, and obtain a total of 23 dropout galaxies at z ∼ 9-16, including two candidates at z phot = 16.25 − 0.46 + 0.24 and 16.41 − 0.55 + 0.66 . We perform thorough comparisons of dropout galaxies found in our work with recent JWST studies, and conclude that our galaxy sample is reliable enough for statistical analyses. We derive the UV luminosity functions at z ∼ 9-16, and confirm that our UV luminosity functions at z ∼ 9 and 12 agree with those determined by other Hubble Space Telescope and JWST studies. The cosmic star formation rate (SFR) density decreases from z ∼ 9 to 12, and perhaps to 16, but the densities at z ∼ 12-16 are higher than the constant star formation efficiency model. Interestingly, there are six bright galaxy candidates at z ∼ 10-16 with M UV < −19.5 mag and M * ∼ 108−9 M ⊙. Because a majority (∼80%) of these galaxies show no signatures of active galactic nuclei in their morphologies, the high cosmic SFR densities and the existence of these UV-luminous galaxies are explained by the lack of suppression of star formation by the UV background radiation at the pre-reionization epoch and/or an efficient UV radiation production by a top-heavy initial mass function with Population III-like star formation.

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    233
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  • A Search for Massive Galaxy Population in a Protocluster of LAEs at z = 2.39 near the Radio Galaxy 53W002

    Naoki Yonekura, Masaru Kajisawa, Erika Hamaguchi, Ken Mawatari, Toru Yamada

    The Astrophysical Journal   930   102  2022年05月  [査読有り]

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    5
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  • Third data release of the Hyper Suprime-Cam Subaru Strategic Program

    Hiroaki Aihara, Yusra AlSayyad, Makoto Ando, Robert Armstrong, James Bosch, Eiichi Egami, Hisanori Furusawa, Junko Furusawa, Sumiko Harasawa, Yuichi Harikane, Bau-Ching Hsieh, Hiroyuki Ikeda, Kei Ito, Ikuru Iwata, Tadayuki Kodama, Michitaro Koike, Mitsuru Kokubo, Yutaka Komiyama, Xiangchong Li, Yongming Liang, Yen-Ting Lin, Robert H. Lupton, Nate B. Lust, Lauren A. MacArthur, Ken Mawatari, Sogo Mineo, Hironao Miyatake, Satoshi Miyazaki, Surhud More, Takahiro Morishima, Hitoshi Murayama, Kimihiko Nakajima, Fumiaki Nakata, Atsushi J. Nishizawa, Masamune Oguri, Nobuhiro Okabe, Yuki Okura, Yoshiaki Ono, Ken Osato, Masami Ouchi, Yen-Chen Pan, Andres A. Plazas Malagon, Paul A. Price, Sophie L. Reed, Eli S. Rykoff, Takatoshi Shibuya, Mirko Simunovic, Michael A. Strauss, Kanako Sugimori, Yasushi Suto, Nao Suzuki, Masahiro Takada, Yuhei Takagi, Tadafumi Takata, Satoshi Takita, Masayuki Tanaka, Shenli Tang, Dan S. Taranu, Tsuyoshi Terai, Yoshiki Toba, Edwin L. Turner, Hisakazu Uchiyama, Bovornpratch Vijarnwannaluk, Christopher Z. Waters, Yoshihiko Yamada, Naoaki Yamamoto, Takuji Yamashita

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   74 ( 2 ) 247 - 272  2022年04月

     概要を見る

    This paper presents the third data release of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), a wide-field multi-band imaging survey with the Subaru 8.2 m telescope. HSC-SSP has three survey layers (Wide, Deep, and UltraDeep) with different area coverages and depths, designed to address a wide array of astrophysical questions. This third release from HSC-SSP includes data from 278 nights of observing time and covers about 670 deg(2) in all five broad-band filters (grizy) at the full depth (similar to 26 mag at 5 sigma depending on filter) in the Wide layer. If we include partially observed areas, the release covers 1470 deg(2). The Deep and UltraDeep layers have similar to 80% of the originally planned integration times, and are considered done, as we have slightly changed the observing strategy in order to compensate for various time losses. There are a number of updates in the image processing pipeline. Of particular importance is the change in the sky subtraction algorithm; we subtract the sky on small scales before the detection and measurement stages, which has significantly reduced the number of false detections. Thanks to this and other updates, the overall quality of the processed data has improved since the previous release. However, there are limitations in the data (for example, the pipeline is not optimized for crowded fields), and we encourage the user to check the quality assurance plots as well as a list of known issues before exploiting the data. The data release website is < https://hsc-release.mtk.nao.ac.jp >.

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    178
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  • A Search for H-Dropout Lyman Break Galaxies at z ∼ 12–16

    Yuichi Harikane, Akio K. Inoue, Ken Mawatari, Takuya Hashimoto, Satoshi Yamanaka, Yoshinobu Fudamoto, Hiroshi Matsuo, Yoichi Tamura, Pratika Dayal, L. Y. Aaron Yung, Anne Hutter, Fabio Pacucci, Yuma Sugahara, Anton M. Koekemoer

    The Astrophysical Journal   929 ( 1 ) 1 - 1  2022年04月

     概要を見る

    Abstract

    We present two bright galaxy candidates at z ∼ 12–13 identified in our H-dropout Lyman break selection with 2.3 deg2 near-infrared deep imaging data. These galaxy candidates, selected after careful screening of foreground interlopers, have spectral energy distributions showing a sharp discontinuity around 1.7 μm, a flat continuum at 2–5 μm, and nondetections at &lt;1.2 μm in the available photometric data sets, all of which are consistent with a z &gt; 12 galaxy. An ALMA program targeting one of the candidates shows a tentative 4σ [O iii] 88 μm line at z = 13.27, in agreement with its photometric redshift estimate. The number density of the z ∼ 12–13 candidates is comparable to that of bright z ∼ 10 galaxies and is consistent with a recently proposed double-power-law luminosity function rather than the Schechter function, indicating little evolution in the abundance of bright galaxies from z ∼ 4 to 13. Comparisons with theoretical models show that the models cannot reproduce the bright end of rest-frame ultraviolet luminosity functions at z ∼ 10–13. Combined with recent studies reporting similarly bright galaxies at z ∼ 9–11 and mature stellar populations at z ∼ 6–9, our results indicate the existence of a number of star-forming galaxies at z &gt; 10, which will be detected with upcoming space missions such as the James Webb Space Telescope, Nancy Grace Roman Space Telescope, and GREX-PLUS.

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    78
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  • 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   509 ( 3 ) 4037 - 4057  2021年12月

     概要を見る

    <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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    27
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  • EMPRESS. III. Morphology, Stellar Population, and Dynamics of Extremely Metal-poor Galaxies (EMPGs): Are EMPGs Local Analogs of High-z Young Galaxies?*

    Yuki Isobe, Masami Ouchi, Takashi Kojima, Takatoshi Shibuya, Kohei Hayashi, Michael Rauch, Shotaro Kikuchihara, Haibin Zhang, Yoshiaki Ono, Seiji Fujimoto, Yuichi Harikane, Ji Hoon Kim, Yutaka Komiyama, Haruka Kusakabe, Chien-Hsiu Lee, Ken Mawatari, Masato Onodera, Yuma Sugahara, Kiyoto Yabe

    The Astrophysical Journal   918 ( 2 ) 54 - 54  2021年09月

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    16
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  • 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   646   A26 - A26  2021年02月

     概要を見る

    <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  ×  108 <italic>L</italic> and 4.0  ×  107 <italic>L</italic>, 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−1, 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>).

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    5
    被引用数
    (Scopus)
  • CHORUS. I. Cosmic HydrOgen Reionization Unveiled with Subaru: Overview

    Akio K Inoue, Satoshi Yamanaka, Masami Ouchi, Ikuru Iwata, Kazuhiro Shimasaku, Yoshiaki Taniguchi, Tohru Nagao, Nobunari Kashikawa, Yoshiaki Ono, Ken Mawatari, Takatoshi Shibuya, Masao Hayashi, Hiroyuki Ikeda, Haibin Zhang, Yongming Liang, Chien-Hsiu Lee, Miftahul Hilmi, Satoshi Kikuta, Haruka Kusakabe, Hisanori Furusawa, Tomoki Hayashino, Masaru Kajisawa, Yuichi Matsuda, Kimihiko Nakajima, Rieko Momose, Yuichi Harikane, Tomoki Saito, Tadayuki Kodama, Shotaro Kikuchihara, Masanori Iye, Tomotsugu Goto

    Publications of the Astronomical Society of Japan   72 ( 6 )  2020年12月

     概要を見る

    <title>Abstract</title>
    To determine the dominant sources for cosmic reionization, the evolution history of the global ionizing fraction, and the topology of the ionized regions, we have conducted a deep imaging survey using four narrow-band (NB) and one intermediate-band (IB) filters on the Subaru/Hyper Suprime-Cam (HSC), called Cosmic HydrOgen Reionization Unveiled with Subaru (CHORUS). The central wavelengths and full-widths-at-half-maximum of the CHORUS filters are, respectively, 386.2 nm and 5.5 nm for NB387, 526.0 nm and 7.9 nm for NB527, 717.1 nm and 11.1 nm for NB718, 946.2 nm and 33.0 nm for IB945, and 971.2 nm and 11.2 nm for NB973. This combination, including NB921 (921.5 nm and 13.5 nm) from the Subaru Strategic Program with HSC (HSC SSP), is carefully designed, as if they were playing a chorus, to observe multiple spectral features simultaneously, such as Lyman continuum, Lyα, C iv, and He ii for $z$ = 2–7. The observing field is the same as that of the deepest footprint of the HSC SSP in the COSMOS field and its effective area is about 1.6 deg2. We present an overview of the CHORUS project, which includes descriptions of the filter design philosophy, observations and data reduction, multiband photometric catalogs, assessments of the imaging quality, measurements of the number counts, and example use cases for the data. All the imaging data, photometric catalogs, masked pixel images, data of limiting magnitudes and point spread functions, results of completeness simulations, and source number counts are publicly available through the HSC SSP database.

    DOI

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  • Testing an indirect method for identifying galaxies with high levels of Lyman continuum leakage

    Satoshi Yamanaka, Akio K. Inoue, Toru Yamada, Erik Zackrisson, Ikuru Iwata, Genoveva Micheva, Ken Mawatari, Takuya Hashimoto, Mariko Kubo

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   498 ( 3 ) 3095 - 3114  2020年11月

     概要を見る

    Using a sample of galaxies at z approximate to 3 with detected Lyman Continuum (LyC) leakage in the SSA22 field, we attempt to verify a proposed indirect method for identifying cases with high LyC escape fraction f(esc) based on measurements of the H beta equivalent width (EW) and the beta slope of the UV continuum. To this end, we present Keck/MOSFIRE H beta emission line flux measurements of LyC galaxies (LCGs) at spectroscopic redshifts z(spec) similar to 3.3, Lyman break galaxies (LBGs) at photometric redshifts z(phot) = 2.7-3.7, and Ly alpha emitters at z(phot) = 3.1. We also reconfirm the spectroscopic redshifts and measure the H beta emission-line fluxes from two LCGs and six LBGs. For the LCG in our sample with the most extreme f(esc), as revealed by the direct detection of LyC photons, we find that the EW(H beta)-beta method gives a broadly consistent estimate for f(esc), although the error bars remain very large. We also discuss how a combination of f(esc) measurements based on direct and indirect methods can shed light on the LyC escape mechanism and the anisotropy of the leakage.

    DOI

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    9
    被引用数
    (Scopus)
  • Cosmological 3D H i Gas Map with HETDEX Lyα Emitters and eBOSS QSOs at z = 2: IGM−Galaxy/QSO Connection and a ∼40 Mpc Scale Giant H ii Bubble Candidate

    Shiro Mukae, Masami Ouchi, Gary J. Hill, Karl Gebhardt, Erin Mentuch Cooper, Donghui Jeong, Shun Saito, Maximilian Fabricius, Eric Gawiser, Robin Ciardullo, Daniel Farrow, Dustin Davis, Greg Zeimann, Steven L. Finkelstein, Caryl Gronwall, Chenxu Liu, Yechi Zhang, Chris Byrohl, Yoshiaki Ono, Donald P. Schneider, Matt J. Jarvis, Caitlin M. Casey, Ken Mawatari

    The Astrophysical Journal   903 ( 1 ) 24 - 24  2020年10月

    DOI

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    11
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  • 3D Distribution Map of HI Gas and Galaxies Around an Enormous Ly$α$ Nebula and Three QSOs at $z=2.3$ Revealed by the HI Tomographic Mapping Technique

    Shiro Mukae, Masami Ouchi, Zheng Cai, Khee-Gan Lee, J. Xavier Prochaska, Sebastiano Cantalupo, Zheng Zheng, Kentaro Nagamine, Nao Suzuki, John D. Silverman, Toru Misawa, Akio K. Inoue, Joseph F. Hennawi, Yuichi Matsuda, Ken Mawatari, Yuma Sugahara, Takashi Kojima, Yoshiaki Ono, Takatoshi Shibuya, Yuichi Harikane, Seiji Fujimoto, Yi-Kuan Chiang, Haibin Zhang, Ryota Kakuma

      896 ( 1 ) 45 - 45  2020年06月

     概要を見る

    We present an IGM HI tomography map in a survey volume of $16 \times 19<br />
    \times 131 \ h^{-3} {\rm comoving \ Mpc}^{3}$ (cMpc$^3$) centered at MAMMOTH-1<br />
    nebula and three neighbouring quasars at $z=2.3$. MAMMOTH-1 nebula is an<br />
    enormous Ly$\alpha$ nebula (ELAN), hosted by a type-II quasar dubbed<br />
    MAMMOTH1-QSO, that extends over $1\ h^{-1}$ cMpc with not fully clear physical<br />
    origin. Here we investigate the HI-gas distribution around MAMMOTH1-QSO with<br />
    the ELAN and three neighbouring type-I quasars, making the IGM HI tomography<br />
    map with a spatial resolution of $2.6\ h^{-1}$ cMpc. Our HI tomography map is<br />
    reconstructed with HI Ly$\alpha$ forest absorption of bright background objects<br />
    at $z=2.4-2.9$: one eBOSS quasar and 16 Keck/LRIS galaxy spectra. We estimate<br />
    the radial profile of HI flux overdensity for MAMMOTH1-QSO, and find that<br />
    MAMMOTH1-QSO resides in a volume with significantly weak HI absorption. This<br />
    suggests that MAMMOTH1-QSO has a proximity zone where quasar illuminates and<br />
    photo-ionizes the surrounding HI gas and suppresses HI absorption, and that the<br />
    ELAN is probably a photo-ionized cloud embedded in the cosmic web. The HI<br />
    radial profile of MAMMOTH1-QSO is very similar to those of three neighbouring<br />
    type-I quasars at $z=2.3$, which is compatible with the AGN unification model.<br />
    We compare the distributions of the HI absorption and star-forming galaxies in<br />
    our survey volume, and identify a spatial offset between density peaks of<br />
    star-forming galaxies and HI gas. This segregation may suggest anisotropic UV<br />
    background radiation created by star-forming galaxy density fluctuations.

    DOI

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    12
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  • ALMA uncovers the [CII] emission and warm dust continuum in a z = 8.31 Lyman break galaxy

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

       2020年01月

     概要を見る

    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 $>$
    80 K, 90% confidence limit), and/or a steep dust-emissivity index ($\beta_{\rm
    dust}$ $>$ 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.

  • Balmer Break Galaxy Candidates at $z \sim 6$: a Potential View on the Star-Formation Activity at $z \gtrsim 14$

    Ken Mawatari, Akio K. Inoue, Takuya Hashimoto, John Silverman, Masaru Kajisawa, Satoshi Yamanaka, Toru Yamada, Iary Davidzon, Peter Capak, Lihwai Lin, Bau-Ching Hsieh, Yoshiaki Taniguchi, Masayuki Tanaka, Yoshiaki Ono, Yuichi Harikane, Yuma Sugahara, Seiji Fujimoto, Tohru Nagao

      889 ( 2 )  2019年12月

     概要を見る

    We search for galaxies with a strong Balmer break (Balmer Break Galaxies;<br />
    BBGs) at $z \sim 6$ over a 0.41 deg$^2$ effective area in the COSMOS field.<br />
    Based on rich imaging data, including data obtained with the Atacama Large<br />
    Millimeter/submillimeter Array (ALMA), three candidates are identified by their<br />
    extremely red $K - [3.6]$ colors as well as by non-detection in X-ray, optical,<br />
    far-infrared (FIR), and radio bands. The non-detection in the deep ALMA<br />
    observations suggests that they are not dusty galaxies but BBGs at $z \sim 6$,<br />
    although contamination from Active Galactic Nuclei (AGNs) at $z \sim 0$ cannot<br />
    be completely ruled out for the moment. Our spectral energy distribution (SED)<br />
    analyses reveal that the BBG candidates at $z \sim 6$ have stellar masses of<br />
    $\approx 5 \times 10^{10} M_{\odot}$ dominated by old stellar populations with<br />
    ages of $\gtrsim 700$ Myr. Assuming that all the three candidates are real BBGs<br />
    at $z \sim 6$, we estimate the stellar mass density (SMD) to be<br />
    $2.4^{+2.3}_{-1.3} \times 10^{4} M_{\odot}$ Mpc$^{-3}$. This is consistent with<br />
    an extrapolation from the lower redshift measurements. The onset of star<br />
    formation in the three BBG candidates is expected to be several hundred million<br />
    years before the observed epoch of $z \sim 6$. We estimate the star-formation<br />
    rate density (SFRD) contributed by progenitors of the BBGs to be 2.4 -- 12<br />
    $\times 10^{-5} M_{\odot}$ yr$^{-1} $Mpc$^{-3}$ at $z &gt; 14$ (99.7\% confidence<br />
    range). Our result suggests a smooth evolution of the SFRD beyond $z = 8$.

    DOI

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  • The role of galaxies and AGN in reionising the IGM -- III : IGM-galaxy cross-correlations at z~6 from 8 quasar fields with DEIMOS and MUSE

    Romain A. Meyer, Koki Kakiichi, Sarah E. I, Bosman, Richar, S. Ellis, Nicolas Laporte, Brant E. Robertson, Emma V. Ryan-Weber, Ken Mawatari, Adi Zitrin

       2019年12月

     概要を見る

    We present improved results of the measurement of the correlation between<br />
    galaxies and the intergalactic medium (IGM) transmission at the end of<br />
    reionisation. We have gathered a sample of $13$ spectroscopically confirmed<br />
    Lyman-break galaxies (LBGs) and $21$ Lyman-$\alpha$ emitters (LAEs) at angular<br />
    separations $20&#039;&#039; \lesssim \theta \lesssim 10&#039;$ ($\sim 0.1-4$ pMpc at $z\sim<br />
    6$) from the sightlines to $8$ background $z\gtrsim 6$ quasars. We report for<br />
    the first time the detection of an excess of Lyman-$\alpha$ transmission spikes<br />
    at $\sim 10-60$ cMpc from LAEs ($3.6\sigma$) and LBGs ($3.1\sigma$). We<br />
    interpret the data with an improved model of the galaxy-Lyman-$\alpha$<br />
    transmission and two-point cross-correlations which includes the enhanced<br />
    photoionisation due to clustered faint sources, enhanced gas densities around<br />
    the central bright objects and spatial variations of the mean free path. The<br />
    observed LAE(LBG)-Lyman-$\alpha$ transmission spike two-point cross-correlation<br />
    function (2PCCF) constrains the luminosity-averaged escape fraction of all<br />
    galaxies contributing to reionisation to $\langle f_{\rm esc} \rangle_{M_{\rm<br />
    UV}&lt;-12} = 0.10_{-0.05}^{+0.17}\,(0.18_{-0.06}^{+0.52})$. We investigate if the<br />
    2PCCF measurement can determine whether bright or faint galaxies are the<br />
    dominant contributors to reionisation. Our results show that a contribution<br />
    from faint galaxies ($M_{\rm UV} &gt; -20 \, (2\sigma)$) is necessary to reproduce<br />
    the observed 2PCCF and that reionisation might be driven by different<br />
    sub-populations around LBGs and LAEs at $z\sim 6$.

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

    Ken Mawatari, Akio K. Inoue, Satoshi Yamanaka, Takuya Hashimoto, Yoichi Tamura

    Proceedings of the International Astronomical Union   15 ( S341 ) 285 - 286  2019年11月

     概要を見る

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

    DOI

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

    Kaho Sunaga, Yoichi Tamura, Minju Lee, Ken Mawatari, Akio K. Inoue, Takuya Hashimoto, Hiroshi Matsuo, Akio Taniguchi

    Proceedings of the International Astronomical Union   15 ( S341 ) 309 - 311  2019年11月

     概要を見る

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

    DOI

  • Dust evolution in galaxies at z > 7

    Tsutomu T. Takeuchi, Ryosuke S. Asano, Sayaka Nagasaki, Takaya Nozawa, Yoichi Tamura, Ken Mawatari, Akio K. Inoue

    Proceedings of the International Astronomical Union   15 ( S341 ) 312 - 313  2019年11月

     概要を見る

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

    DOI

  • Detections of [O III] 88 {\ensuremath{\mu } }m in two quasars in the reionization epoch

    馬渡 健

    Publications of the Astronomical Society of Japan   71 ( 6 )  2019年09月  [査読有り]

  • The absence of [C II] 158 μm emission in spectroscopically confirmed galaxies at z &gt; 8

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

    Monthly Notices of the Royal Astronomical Society    2019年07月  [査読有り]

     概要を見る

    The scatter in the relationship between the strength of [C II] 158 μm emission and the star formation rate at high redshift has been the source of much recent interest. Although the relationship is well established locally, several intensely star-forming galaxies have been found whose [C II] 158 μm emission is either weak, absent, or spatially offset from the young stars. Here we present new ALMA data for the two most distant gravitationally lensed and spectroscopically confirmed galaxies, A2744_YD4 at z = 8.38 and MACS1149_JD1 at z = 9.11, both of which reveal intense [O III] 88 μm emission. In both cases we provide stringent upper limits on the presence of [C II] 158 μm with respect to [O III] 88 μm. We review possible explanations for this apparent redshift-dependent [C II] deficit in the context of our recent hydrodynamical simulations. Our results highlight the importance of using several emission line diagnostics with ALMA to investigate the nature of the interstellar medium in early galaxies....

    DOI

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  • SILVERRUSH. IX. Ly$α$ Intensity Mapping with Star-Forming Galaxies at $z=5.7$ and $6.6$: Ly$α$ Emission Extended at $>150$ comoving kpc Beyond the Virial-Radius Scale of Galaxy Dark Matter Halos

    Ryota Kakuma, Masami Ouchi, Yuichi Harikane, Akio K Inoue, Yutaka Komiyama, Haruka Kusakabe, Chien-Hsiu Liu, Yuichi Matsuda, Yoshiki Matsuoka, Ken Mawatari, Rieko Momose, Yoshiaki Ono, Takatoshi Shibuya, Yoshiaki Taniguchi

      916 ( 1 ) 22 - 22  2019年06月

     概要を見る

    We present results of the cross-correlation Lya intensity mapping with<br />
    Subaru/Hyper Suprime-Cam (HSC) ultra-deep narrowband images and Lya emitters<br />
    (LAEs) at $z=5.7$ and $6.6$ in a total area of $4$ deg$^2$. Although<br />
    overwhelming amount of data quality controls have been performed for the<br />
    narrowband images and the LAE samples, we further conduct extensive analysis<br />
    evaluating systematics of large-scale point spread function wings, sky<br />
    subtractions, and unknown errors on the basis of physically uncorrelated<br />
    signals and sources found in real HSC images and object catalogs, respectively.<br />
    Removing the systematics, we carefully calculate cross-correlations between Lya<br />
    intensity of the narrowband images and the LAEs. We identify very diffuse Lya<br />
    emission with the $3\sigma$ ($2\sigma$) significance at $&gt;150$ comoving kpc<br />
    (ckpc) far from the LAEs at $z = 5.7$ ($6.6$), beyond a virial radius of<br />
    star-forming galaxies with $M_\mathrm{h} \sim 10^{11} M_\odot$. The diffuse Lya<br />
    emission possibly extends up to $1,000$ ckpc with the surface brightness of<br />
    $10^{-20}-10^{-19}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$. We confirm that the<br />
    small-scale ($&lt;150$ ckpc) Lya radial profiles of LAEs in our Lya intensity maps<br />
    are consistent with those obtained by recent MUSE observations (Leclercq et al.<br />
    2017). Comparisons with numerical simulations suggest that the large-scale<br />
    ($\sim 150-1,000$ ckpc) Lya emission are not explained by unresolved faint<br />
    sources of neighboring galaxies including satellites, but by a combination of<br />
    Lya photons emitted from the central LAE and other unknown sources, such as a<br />
    cold-gas stream and galactic outflow. We find no evolution in the Lya radial<br />
    profiles of our LAEs from $z=5.7$ to $6.6$, where theoretical models predict a<br />
    flattening of the profile slope made by cosmic reionization, albeit with our<br />
    moderately large observational errors.

    DOI

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  • Early Low-Mass Galaxies and Star-Cluster Candidates at z~6-9 Identified by the Gravitational Lensing Technique and Deep Optical/Near-Infrared Imaging

    Shotaro Kikuchihara, Masami Ouchi, Yoshiaki Ono, Ken Mawatari, Jacopo Chevallard, Yuichi Harikane, Takashi Kojima, Masamune Oguri, Gustavo Bruzual, Stephane Charlot

      893 ( 1 )  2019年05月

     概要を見る

    We present very faint dropout galaxies at z~6-9 with a stellar mass M* down<br />
    to M*~10^6Mo that are found in deep optical/near-infrared (NIR) images of the<br />
    full data sets of the Hubble Frontier Fields (HFF) program in conjunction with<br />
    deep ground-based and Spitzer images and gravitational lensing magnification<br />
    effects. We investigate stellar populations of the HFF dropout galaxies with<br />
    the optical/NIR photometry and BEAGLE models made of self-consistent stellar<br />
    population synthesis and photoionization models, carefully including strong<br />
    nebular emission impacting on the photometry. We identify 357 galaxies with<br />
    M*~10^6-10^9Mo, and find that a stellar mass to UV luminosity L_UV ratio<br />
    M*/L_UV is nearly constant at M*~10^6-10^9Mo. Our best-estimate M*/L_UV<br />
    function is comparable to a model of star-formation duration time of 100 Myr,<br />
    but 2-7 times higher than the one of 10 Myr assumed in a previous study (at the<br />
    5sigma level) that would probably underestimate M* of faint galaxies. We derive<br />
    the galaxy stellar mass functions (GSMFs) at z~6-9 that agree with those<br />
    obtained by previous studies with no M*/L_UV assumptions at M*&gt;~10^8Mo, and<br />
    that extends to M*~10^6Mo. Estimating the stellar mass densities rho* with the<br />
    GSMFs, we find that rho* smoothly increases from log(rho*/[Mo Mpc^(-3)])=5.91<br />
    +0.75/-0.65 at z~9 to 6.21 +0.39/-0.37 at z~6-7, which is consistent with the<br />
    one estimated from star-formation rate density measurements. In conjunction<br />
    with the estimates of the galaxy effective radii R_e on the source plane, we<br />
    have pinpointed two objects with low stellar masses (M*&lt;=10^7Mo) and very<br />
    compact morphologies (R_e&lt;=40 physical pc) that are comparable with those of<br />
    globular clusters (GCs) in the Milky Way today. These objects are candidates of<br />
    star clusters that should be a part or a dominant component of high-redshift<br />
    low-mass galaxy, some of which may be related to GCs today.

    DOI

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    被引用数
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  • Extreme variations in star formation activity in the first galaxies

    Christian Binggeli, Erik Zackrisson, Xiangcheng Ma, Akio K. Inoue, Anton Vikaeus, Takuya Hashimoto, Ken Mawatari, Ikkoh Shimizu, Philip F. Hopkins

    Proceedings of the International Astronomical Union   15 ( 341 ) 226 - 230  2019年

     概要を見る

    Recently, spectroscopic detections of O[III] 88 μm and Ly-α emission lines from the z 9.1 galaxy MACS1149-JD1 have been presented, and with these, some interesting properties of this galaxy were uncovered. One such property is that MACS1149-JD1 exhibits a significant Balmer break at around rest-frame 4000 Å, which may indicate that the galaxy has experienced large variations in star formation rate prior to z ∼ 9, with a rather long period of low star formation activity. While some simulations predict large variations in star formation activity in high-redshift galaxies, it is unclear whether the simulations can reproduce the kind of variations seen in MACS1149-JD1. Here, we utilize synthetic spectra of simulated galaxies from two simulation suites in order to study to what extent these can accurately reproduce the spectral features (specifically the Balmer break) observed in MACS1149-JD1. We show that while the simulations used in this study produce galaxies with varying star formation histories, galaxies such as MACS1149-JD1 would be very rare in the simulations. In principle, future observations with the James Webb Space Telescope may tell us if MACS1149-JD1 represents something rare, or if such galaxies are more common than predicted by current simulations.

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  • Balmer breaks in simulated galaxies at z &gt; 6

    Christian Binggeli, Erik Zackrisson, Xiangcheng Ma, Akio K. Inoue, Anton Vikaeus, Takuya Hashimoto, Ken Mawatari, Ikkoh Shimizu, Daniel Ceverino

    Monthly Notices of the Royal Astronomical Society   489 ( 3 ) 3827 - 3835  2019年

     概要を見る

    Photometric observations of the spectroscopically confirmed z ≈ 9.1 galaxy MACS1149-JD1 have indicated the presence of a prominent Balmer break in its spectral energy distribution, which may be interpreted as due to very large fluctuations in its past star formation activity. In this paper, we investigate to what extent contemporary simulations of high-redshift galaxies produce star formation rate variations sufficiently large to reproduce the observed Balmer break of MACS1149-JD1. We find that several independent galaxy simulations are unable to account for Balmer breaks of the inferred size, suggesting that MACS1149-JD1 either must be a very rare type of object or that our simulations are missing some key ingredient. We present predictions of spectroscopic Balmer break strength distributions for z ≈ 7-9 galaxies that may be tested through observations with the upcoming James Webb Space Telescope and also discuss the impact that various assumptions on dust reddening, Lyman continuum leakage, and deviations from a standard stellar initial mass function would have on the results.

    DOI

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    被引用数
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  • Enhancement of H I absorption associated with the z = 3.1 large-scale proto-cluster and characteristic structures with AGNs sculptured over Gpc scale in the SSA22 field

    Hayashino} T, Inoue} A.~K, Kousai} K, Kashikawa} N, Mawatari} K, Matsuda} Y, Tejos} N, Prochaska} J, Iwata} I, Noll} S, Burgarella} D, Yamada} T, Akiyama} M

    \mnras   484 ( 4 ) 5868 - 5887  2019年  [査読有り]

    DOI

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    8
    被引用数
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  • CHORUS. III. Photometric and Spectroscopic Properties of Ly$α$ Blobs at $z=4.9-7.0$

    Zhang} Haibin, Ouchi} Masami, Itoh} Ryohei, Shibuya} Takatoshi, Ono} Yoshiaki, Harikane} Yuichi, Inoue, Akio K, Rauch} Michael, Kikuchihara} Shotaro, Nakajima} Kimihiko, Yajima} Hidenobu, Arata} Shohei, Abe} Makito, Iwata} Ikuru, Kashikawa} Nobunari, Kawanomoto} Satoshi, Kikuta} Satoshi, Kobayashi, Masakazu, Kusakabe} Haruka, Mawatari} Ken, Nagao} Tohru, Shimasaku} Kazuhiro, Taniguchi} Yoshiaki

    arXiv e-prints     arXiv:1905.09841  2019年  [査読有り]

  • 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

    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 (Submitted)    2018年06月

     概要を見る

    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.

    DOI

    Scopus

    160
    被引用数
    (Scopus)
  • "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $μ$m, [CII] 158 $μ$m, and Dust Continuum with ALMA

    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 (submitted)    2018年06月

     概要を見る

    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.

    DOI

    Scopus

    180
    被引用数
    (Scopus)
  • ``Big Three Dragons'': a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $μ$m, [CII] 158 $μ$m, and Dust Continuum with ALMA

    Hashimoto} T, Inoue} A.~K, Mawatari} K, Tamura} Y, Matsuo} H, Furusawa} H, Harikane} Y, Shibuya} T, Knudsen} K.~K, Kohno} K, Ono} Y, Zackrisson} E, Okamoto} T, Kashikawa} N, Oesch} P.~A, Ouchi} M, Ota} K, Shimizu} I, Taniguchi} Y, Umehata} H, Watson} D

    ArXiv e-prints    2018年06月  [査読有り]

    DOI

    Scopus

    180
    被引用数
    (Scopus)
  • CHORUS II. Subaru/HSC Determination of the Ly$\alpha$ Luminosity Function at $z=7.0$: Constraints on Cosmic Reionization Model Parameter

    Ryohei Itoh, Masami Ouchi, Haibin Zhang, Akio K. Inoue, Ken Mawatari, Takatoshi Shibuya, Yuichi Harikane, Yoshiaki Ono, Haruka Kusakabe, Kazuhiro Shimasaku, Seiji Fujimoto, Ikuru Iwata, Masaru Kajisawa, Nobunari Kashikawa, Satoshi Kawanomoto, Yutaka Komiyama, Chien-Hsiu Lee, Tohru Nagao, Yoshiaki Taniguchi

    Astrophysical Journal (Submitted)    2018年05月

     概要を見る

    We present the Ly$\alpha$ luminosity function (LF) derived from 34 Ly$\alpha$<br />
    emitters (LAEs) at $z=7.0$ on the sky of $3.1$ deg$^2$, the largest sample<br />
    compared to those in the literature obtained at a redshift $z\gtrsim7$. The LAE<br />
    sample is made by deep large-area Subaru narrowband observations conducted by<br />
    the Cosmic HydrOgen Reionization Unveiled with Subaru (CHORUS) project. The<br />
    $z=7.0$ Ly$\alpha$ LF of our project is consistent with those of the previous<br />
    DECam and Subaru studies at the bright and faint ends, respectively, while our<br />
    $z=7.0$ Ly$\alpha$ LF has uncertainties significantly smaller than those of the<br />
    previous study results. Exploiting the small errors of our measurements, we<br />
    investigate the shape of the faint to bright-end Ly$\alpha$ LF. We find that<br />
    the $z=7.0$ Ly$\alpha$ LF shape can be explained by the steep slope of $\alpha<br />
    \simeq -2.5$ suggested at $z=6.6$, and that there is no clear signature of a<br />
    bright-end excess at $z\simeq 7$ claimed by the previous work, which was<br />
    thought to be made by the ionized bubbles around bright LAEs whose Ly$\alpha$<br />
    photons could easily escape from the partly neutral IGM at $z \simeq 7$. We<br />
    estimate the Ly$\alpha$ luminosity densities (LDs) with Ly$\alpha$ LFs at<br />
    $z\simeq 6-8$ given by our and the previous studies, and compare the evolution<br />
    of the UV-continuum LD estimated with dropouts. The Ly$\alpha$ LD monotonically<br />
    decreases from $z\sim 6$ to $8$, and evolves stronger than the UV-continuum LD,<br />
    indicative of the Ly$\alpha$ damping wing absorption of the IGM towards the<br />
    heart of the reionization epoch.

  • Mapping of HI Absorption Structure in the SSA22 Protocluster at z = 3.1

    Mawatari} K

    Early stages of Galaxy Cluster Formation     19  2017年07月  [査読有り]

    DOI

  • 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   467 ( 4 ) 3951 - 3962  2017年06月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    16
    被引用数
    (Scopus)
  • 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   352   1559 - 1562  2016年06月  [査読有り]

     概要を見る

    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.

    DOI

    Scopus

    182
    被引用数
    (Scopus)
  • Possible identification of massive and evolved galaxies at z greater than or similar to 5

    Ken Mawatari, Toru Yamada, Giovanni G. Fazio, Jia-Sheng Huang, Matthew L. N. Ashby

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   68 ( 3 ) 46  2016年06月  [査読有り]

     概要を見る

    We report on the identification of the old stellar population galaxy candidates at z greater than or similar to 5. We developed a new infrared color selection scheme to isolate galaxies with the strong Balmer breaks at z greater than or similar to 5, and applied it to the ultra-deep and wide infrared survey data from the Spitzer Extended Deep Survey (SEDS) and the UKIRT Infrared Deep Sky Survey. The eight objects satisfying K - [3.6] &gt; 1.3 and K - [3.6] &gt; 2.4([3.6] - [4.5]) + 0.6 are selected in the 0.34 deg(2) SEDS Ultra Deep Survey field. Rich multi-wavelength imaging data from optical to far-infrared are also used to reject blending sources and strong nebular line emitters, and we finally obtained the three most likely evolved galaxies at z greater than or similar to 5. Their stacked spectral energy distribution is fitted well with the old stellar population template with M-* = (7.5 +/- 1.5) x 10(10) M-circle dot, star formation rate = 0.9 +/- 0.2M(circle dot) yr(-1), dust A(V) &lt; 1, and age = 0.7 +/- 0.4 Gyr at z = 5.7 +/- 0.6, where the dusty star-forming galaxies at z similar to 2.8 are disfavored because of the faintness in the 24 mu m. The stellar mass density of these evolved galaxy candidates, (6 +/- 4) x 10(4) M-circle dot Mpc(-3), is much lower than that of star-forming galaxies, but the non-zero fraction suggests that initial star-formation and quenching have been completed by z similar to 6.

    DOI

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    24
    被引用数
    (Scopus)
  • DISCOVERY OF A DAMPED Ly alpha ABSORBER AT z=3.3 ALONG A GALAXY SIGHT-LINE IN THE SSA22 FIELD

    K. Mawatari, A. K. Inoue, K. Kousai, T. Hayashino, R. Cooke, J. X. Prochaska, T. Yamada, Y. Matsuda

    ASTROPHYSICAL JOURNAL   817 ( 2 ) 161  2016年02月  [査読有り]

     概要を見る

    Using galaxies as background light sources to map the Ly alpha absorption lines is a novel approach to study Damped Ly alpha Absorbers (DLAs). We report the discovery of an intervening z = 3.335 +/- 0.007 DLA along a galaxy sight-line identified among 80 Lyman Break Galaxy (LBG) spectra obtained with our Very Large Telescope/Visible Multi-Object Spectrograph survey in the SSA22 field. The measured DLA neutral hydrogen (H-I) column density is log(N-H I/cm(-2)) = 21.68 +/- 0.17. The DLA covering fraction over the extended background LBG is &gt;70% (2 sigma), yielding a conservative constraint on the DLA area of greater than or similar to 1 kpc(2). Our search for a counterpart galaxy hosting this DLA concludes that there is no counterpart galaxy with star formation rate larger than a few M-circle dot yr(-1), ruling out an unobscured violent star formation in the DLA gas cloud. We also rule out the possibility that the host galaxy of the DLA is a passive galaxy with M-* greater than or similar to 5 x 10(10) M-circle dot or a heavily dust-obscured galaxy with E(B - V) greater than or similar to 2. The DLA may coincide with a large-scale overdensity of the spectroscopic LBGs. The occurrence rate of the DLA is compatible with that of DLAs found in QSO sight-lines.

    DOI

    Scopus

    11
    被引用数
    (Scopus)
  • K-3.6$\mu$mで赤い銀河の性質:赤方偏移5以上のpassive銀河候補

    馬渡 健

    東北大学    2015年03月  [査読有り]

  • SPT-CL J2040-4451: AN SZ-SELECTED GALAXY CLUSTER AT z=1.478 WITH SIGNIFICANT ONGOING STAR FORMATION

    M. B. Bayliss, M. L. N. Ashby, J. Ruel, M. Brodwin, K. A. Aird, M. W. Bautz, B. A. Benson, L. E. Bleem, S. Bocquet, J. E. Carlstrom, C. L. Chang, H. M. Cho, A. Clocchiattii, T. M. Crawford, A. T. Crites, S. Desai, M. A. Dobbs, J. P. Dudley, R. J. Foley, W. R. Forman, E. M. George, D. Gettings, M. D. Gladders, A. H. Gonzalez, T. de Haan, N. W. Halverson, F. W. High, G. P. Holder, W. L. Holzapfel, S. Hoover, J. D. Hrubes, C. Jones, M. Joy, R. Keisler, L. Knox, A. T. Lee, E. M. Leitch, J. Liu, M. Lueker, D. Luong-Van, A. Mantz, D. P. Marrone, K. Mawatari, M. McDonald, J. J. McMahon, J. Mehl, S. S. Meyer, E. D. Miller, L. Mocanu, J. J. Mohr, T. E. Montroy, S. S. Murray, S. Padin, T. Plagge, C. Pryke, C. L. Reichardt, A. Rest, J. E. Ruhl, B. R. Saliwanchik, A. Saro, J. T. Sayre, K. K. Schaffer, E. Shirokoff, J. Song, B. Stalder, R. Suhada, H. G. Spieler, S. A. Stanford, Z. Staniszewski, A. A. Stark, K. Story, C. W. Stubbs, A. van Engelen, K. Vanderlinde, J. D. Vieira, A. Vikhlinin, R. Williamson, R. Zahn, A. Zenteno

    ASTROPHYSICAL JOURNAL   794 ( 1 ) 12  2014年10月  [査読有り]

     概要を見る

    SPT-CL J2040-4451-spectroscopically confirmed at z = 1.478-is the highest-redshift galaxy cluster yet discovered via the Sunyaev-Zel'dovich effect. SPT-CL J2040-4451 was a candidate galaxy cluster identified in the first 720 deg(2) of the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, and has been confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+ IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O Pi]lambda lambda 3727 emission. SPT-CL J2040-4451 has an SZ-measured mass of M-500,(SZ) = 3.2 +/- 0.8 x 10(14)M(circle dot) h(-1) 70, corresponding to M-200,M- (SZ) = 5.8 +/- 1.4 x 10(14)M(circle dot) h(70-)(1.) The velocity dispersion measured entirely from blue star-forming members is sv = 1500 +/- 520 km s(-1). The prevalence of star-forming cluster members (galaxies with &gt; 1.5M(circle dot) yr(-1)) implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z greater than or similar to 1.4. We also compute the probability of finding a cluster as rare as this in the SPT-SZ survey to be &gt; 99%, indicating that its discovery is not in tension with the concordance Lambda CDM cosmological model.

    DOI

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    42
    被引用数
    (Scopus)
  • Characterization of the distribution of the Llyαemitters in the 53W002 field at z = 2.4

    Ken Mawatari, Toru Yamada, Yuki Nakamura, Tomoki Hayashino, Yuichi Matsuda

    Astrophysical Journal   759 ( 2 ) 133  2012年11月  [査読有り]

     概要を見る

    We present the results of our wide-field narrow band imaging of the field<br />
    around the radio galaxy 53W002 at z = 2.390 with Subaru/Suprime-Cam. A custom<br />
    made filter NB413 centered at 4140 \AA\ with the width of 83 \AA\ is used to<br />
    observe the 31&#039; x 24&#039; area around the radio galaxy. We detected 204 Ly\alpha<br />
    emitters (LAEs) at z = 2.4 with a rest frame equivalent width larger than 25<br />
    \AA\ to the depth of 26 AB mag (in NB413). The entire LAE population in the<br />
    53W002 field has an average number density and distributions of equivalent<br />
    width and size that are similar to those of other fields at z ~ 2. We identify<br />
    a significant high density region (53W002F-HDR) that spreads over ~ 5&#039; x 4&#039;<br />
    near 53W002 where the LAE number density is nearly four times as large as the<br />
    average of the entire field. Using the probability distribution function of<br />
    density fluctuation, we evaluate the rareness probability of the 53W002F-HDR to<br />
    be 0.9^{+2.4}_{-0.62}%, which corresponds to a moderately rich structure. No<br />
    notable environmental dependency at the comoving scale of 10 Mpc is found for<br />
    the distributions of the Ly\alpha equivalent width and luminosity in the field.<br />
    We also detected 4 Ly\alpha blobs (LABs), one of which is newly discovered.<br />
    They are all found to be located in the rims of high density regions. The<br />
    biased location and unique morphologies in Ly\alpha suggest that galaxy<br />
    interaction play a key role in their formation.

    DOI

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    24
    被引用数
    (Scopus)
  • WISH for deep and wide NIR surveys

    Toru Yamada, Ikuru Iwata, Makiko Ando, Mamoru Doi, Tomotsugu Goto, Yuji Ikeda, Masatoshi Imanishi, Akio K. Inoue, Satoru Iwamura, Nobuyuki Kawai, Masakazu A. R. Kobayashi, Tadayuki Kodama, Yutaka Komiyama, Mariko Kubo, Hideo Matsuhara, Ken Mawatari, Matsuokak Yoshiki, Tomoki Morokuma, Hidehiko Nakaya, Kouji Ohta, Atsushi Okamoto, Sinki Oyabu, Yoichi Sato, Hiroyuki Sugita, Ryo Tsutsui, Chihiro Tokoku, Jun Toshikawa, Saku Tsuneta, Takehiko Wada, Kiyoto Yabe, Naoki Yasuda, Daisuke Yonetoku

    SPACE TELESCOPES AND INSTRUMENTATION 2012: OPTICAL, INFRARED, AND MILLIMETER WAVE   8442   84421A  2012年  [査読有り]

     概要を見る

    WISH, Wide-field Imaging Surveyor for High-redshiftt, is a space mission concept to conduct very deep and wide-field surveys at near infrared wavelength at 1-5 mu m to study the properties of galaxies at very high redshift beyond the epoch of cosmic reionization. The concept has been developed and studied since 2008 to be proposed for future JAXA/ISAS mission. WISH has a 1.5m-diameter primary mirror and a wide-field imager covering 850 arcmin(2) The pixel scale is 0.155 arcsec for 18 mu m pitch, which properly samples the diffraction-limited image at 1.5 mu m. The main program is Ultra Deep Survey (UDS) covering 100 deg(2) down to 28AB mag at least in five broad bands We expect to detect &gt;10(4) galaxies at z=8-9, 10(3)-10(4) galaxies at z=11-12, and 50-100 galaxies at z&gt;14, many of which can be feasible targets for deep spectroscopy with Extremely Large Telescopes. With recurrent deep observations, detection and light curve monitoring for type-Ia SNe in rest-frame infrared wavelength is also conducted, which is another main science goal of the mission. During the in-orbit 5 years observations, we expect to detect and monitor &gt;2000 type-Ia SNe up to z similar to 2. WISH also conducts Ultra Wide Survey, covering 1000deg(2) down to 24-25AB mag as well as Extreme Survey, covering a limited number of fields of view down to 29-30AB mag. We here report the progress of the WISH project including the basic telescope and satellite design as well as the results of the test for a proto-model of the flip-type filter exchanger which works robustly near 100K.

    DOI

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    9
    被引用数
    (Scopus)
  • An H alpha search for overdense regions at z=2.23

    Y. Matsuda, Ian Smail, J. E. Geach, P. N. Best, D. Sobral, I. Tanaka, F. Nakata, K. Ohta, J. Kurk, I. Iwata, Rich Bielby, J. L. Wardlow, R. G. Bower, R. J. Ivison, T. Kodama, T. Yamada, K. Mawatari, M. Casali

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   416 ( 3 ) 2041 - 2059  2011年09月  [査読有り]

     概要を見る

    We present the results of a narrow-band (H(2)S1, lambda(c) = 2.121 mu m, delta lambda = 0.021 mu m) imaging search with Wide Field Camera/United Kingdom Infrared Telescope for Ha emitters (HAEs) around several potential signposts of rare (similar to 10(-7)-10(-8) comoving Mpc(-3)) overdense regions at z = 2.23: an overdensity of quasi-stellar objects [QSOs; 2dF QSO Redshift Survey (2QZ) cluster], a powerful, high-redshift radio galaxy (HzRG) and a concentration of submillimetre galaxies (SMGs) and optically faint radio galaxies (OFRGs). In total, we detect 137 narrowband emitter candidates down to emission-line fluxes of 0.5-1 x 10(-16) erg s(-1) cm(-2), across a total area of 0.56 deg(2) (2.1 x 10(5) comoving Mpc(3) at z = 2.23) in these fields. The BzK colours of the emitters suggest that at least 80 per cent of our sample are likely to be HAEs at z = 2.23. This is one of the largest HAE samples known at z greater than or similar to 2. Although there is no evidence for large-scale (20 comoving Mpc) overdensities of the emitters around the targets, we find modest (similar to 3 sigma) local overdensities associated with all three targets on smaller scales (5-10 comoving Mpc). In the 2QZ cluster field, the structure appears to be connecting the QSOs, while in the HzRG and SMG/OFRG fields, the structures are seen only in the vicinities of the targets. Our results suggest that these rare targets are located in local overdensities of galaxies, rather than average density regions, although it is not clear whether these structures are likely to evolve into rare, rich clusters. The K-band magnitudes and the Ha equivalent widths of the emitters are weakly correlated with the overdensities of the emitters: emitters in overdense regions are more evolved systems compared to those in underdense regions at z = 2.23. We find several examples of extended HAEs near to the targets, including a striking example with a spatial extent of 7.5 arcsec (60 kpc at z = 2.23) in the 2QZ cluster field, suggesting that these are relatively common in overdense regions. We conclude that narrow-band Ha surveys are efficient routes to map overdense regions at high redshifts and thus to understand the relation between the growth of galaxies and their surrounding large-scale structures.

    DOI

    Scopus

    44
    被引用数
    (Scopus)

▼全件表示

講演・口頭発表等

  • アルマ望遠鏡、132.8 億光年かなたの銀河に酸素 を発見 – 酸素の最遠方検出記録をさらに更新

    橋本拓也, 馬渡健, 井上昭雄, 平松正顕

    記者会見(発表機関:大阪産業大学、名古屋大学、東京 大学宇宙線研究所、国立天文台)  

    発表年月: 2018年05月

共同研究・競争的資金等の研究課題

  • 遠方passive銀河探査から解明する宇宙最初期の星形成活動

    日本学術振興会  科学研究費助成事業

    研究期間:

    2020年04月
    -
    2024年03月
     

    馬渡 健

     概要を見る

    本研究課題は、宇宙最初期における銀河内の星形成がダークマターの重力集積のみで決定される現象なのか、あるいは超新星爆発などガスの輻射流体的効果を大きく受けたプロセスなのかを判別することを目的とする。2つのシナリオの切り分けのために、赤方偏移10以上(宇宙年齢5億年以前)での宇宙全体の星形成率密度を調べる。赤方偏移10以上での星形成活動を直接的に調べる観測研究は新型宇宙望遠鏡JWSTの打ち上げに向けて議論が活発になされているが、本研究では赤方偏移6付近の年老いた銀河(passive銀河)の探査を通じて制限をかける独自かつ相補的なアプローチをとる。
    2021年度の実施状況について、まず昨年度に提出したJWST宇宙望遠鏡への観測提案が残念ながら不採択となった。そこで、COSMOS天域で行われた自身の先行研究(Mawatari et al. 2020, APJ, 889, 137)と同様のサンプルセレクション解析を同領域の最新のデータセット(COSMOS2020; Weaver et al. 2022, ApJS, 258, 11)に対して適用した。COSMOSチームの研究者とも意見交換しながらカタログ測光データの解析を慎重に行った結果、約10天体の遠方passive銀河候補を見つけた。波長2ミクロン付近の近赤外光データの感度が若干良くなったためサンプルセレクションが改善されたが、それ以外の波長域ではデータの質が自身の先行研究から変わらないため、より詳細なSED解析には進んでいない。海外の共同研究者と議論した結果、JWST宇宙望遠鏡のデータが必須であることを確認し、初期科学運用データが公開され次第その解析に取り組む方針を立てた。JWSTデータ解析に慣れるために、共同研究者として参加している他のJWST観測プログラムにおいて観測準備・データ処理計画などに積極的に参加した。

  • 60~110億年前の宇宙における銀河の形成・進化の環境依存性に関する研究

    日本学術振興会  特別研究員奨励費

    研究期間:

    2013年04月
    -
    2015年03月
     

    馬渡 健

Misc

  • RIOJA:z=6.81銀河のJWST+ALMA解析(2)ISM物理状態の推定

    碓氷光崇, 橋本拓也, 馬渡健, 大曽根渉, 井上昭雄, 菅原悠馬, REN Yi, 札本佳伸, 田村陽一, 萩本将都, 橋ヶ谷武志, BAKX T.J.L.C., 仲里佑利奈, 吉田直紀, 松尾宏, ALVAREZ-MARQUES J., CORINA L., COSTANTIN L.

    日本天文学会年会講演予稿集   2024  2024年

    J-GLOBAL

  • RIOJA:z=6.81銀河のJWST+ALMA解析(1)SEDから探る多成分系の性質

    馬渡健, 橋本拓也, 碓氷光崇, 大曽根渉, 井上昭雄, 菅原悠馬, REN Yi, 札本佳伸, 田村陽一, 萩本将都, 橋ヶ谷武志, BAKX T.J.L.C., 仲里佑利奈, 吉田直紀, 松尾宏, ALVAREZ-MARQUES J., CORINA L., COSTANTIN L.

    日本天文学会年会講演予稿集   2024  2024年

    J-GLOBAL

  • RIOJA:赤方偏移7.9の原始銀河団コア領域にある銀河の輝線比診断

    大曽根渉, 橋本拓也, 馬渡健, 碓氷光崇, 井上昭雄, 菅原悠馬, REN Yi, 札本佳伸, 田村陽一, 萩本将都, 橋ヶ谷武志, BAKX Tom, 仲里佑利奈, 吉田直紀, 松尾宏, ALVAREZ-MARQUES J., CORINA L.

    日本天文学会年会講演予稿集   2024  2024年

    J-GLOBAL

  • GREX-PLUS Science Book

    GREX-PLUS Science Team, Akio K. Inoue, Yuichi Harikane, Takashi Moriya, Hideko Nomura, Shunsuke Baba, Yuka Fujii, Naoteru Gouda, Yasuhiro Hirahara, Yui Kawashima, Tadayuki Kodama, Yusei Koyama, Hiroyuki Kurokawa, Taro Matsuo, Yoshiki Matsuoka, Shuji Matsuura, Ken Mawatari, Toru Misawa, Kentaro Nagamine, Kimihiko Nakajima, Shota Notsu, Takafumi Ootsubo, Kazumasa Ohno, Hideo Sagawa, Takashi Shimonishi, Ken-ichi Tadaki, Michihiro Takami, Tsuyoshi Terai, Yoshiki Toba, Takuji Yamashita, Chikako Yasui

    arXiv e-Print    2023年04月

    機関テクニカルレポート,技術報告書,プレプリント等  

    DOI

  • JWST/NIRSpecによるz~3-4 quiescent銀河の分光観測

    佐藤理究, 井上昭雄, 播金優一, 札本佳伸, 札本佳伸, 山中郷史, 馬渡健, 橋本拓也, 田村陽一, 松尾宏

    日本天文学会年会講演予稿集   2023  2023年

    J-GLOBAL

  • 多相星間物質モデルで探る赤方偏移z=8.312の星形成銀河における中性ガスの“porosity”の推定

    萩本将都, 田村陽一, 梅畑豪紀, 谷口暁星, BAKX Tom, 井上昭雄, 菅原悠馬, 札本佳伸, 橋本拓也, 馬渡健, 播金優一, 松尾宏

    日本天文学会年会講演予稿集   2023  2023年

    J-GLOBAL

  • JWST/MSAシャッターのスリットロスによる物理量測定への影響

    碓氷光崇, 橋本拓也, 馬渡健, 仲里佑利奈, 吉田直紀, 井上昭雄, 菅原悠馬, 札本佳伸, REN Yi, 田村陽一, 萩本将都, BAKX Tom, 橋ヶ谷武志, 松尾宏

    日本天文学会年会講演予稿集   2023  2023年

    J-GLOBAL

  • JWSTとALMAによる最遠方の原始銀河団コアの同定:宇宙年齢6.5億年における環境効果の始まり

    橋本拓也, ALVAREZ-MARQUEZ J., 札本佳伸, 札本佳伸, COLINA L., 井上昭雄, 仲里佑利奈, CEVERINO D., 吉田直紀, COSTANTIN L., 菅原悠馬, GOMEZ A.Crespo, BLANCO-PRIETO C., 馬渡健, ARRIBAS S., MARQUES-CHAVES R., PEREIRA-SANTAELLA M., BAKX T.J.L., BAKX T.J.L., 萩本将都, 橋ヶ谷武志, 松尾宏, 田村陽一, 碓氷光崇, 任毅

    日本天文学会年会講演予稿集   2023  2023年

    J-GLOBAL

  • 電離光子放射天体Mrk54における[O III]88μmと[C II]158μmの検出とその意味-高赤方偏移ALMA研究への示唆 II

    浦遼太, 橋本拓也, 久野成夫, 矢島秀伸, 井上昭雄, 菅原悠馬, 札本佳伸, FADDA Dario, 田村陽一, 萩本将都, BAKX Tom, 松尾宏, 馬渡健, 山中郷史, HAYES Matthew, PUSCHNIG Johannes, ZACKRISSON Erick, 吉田直紀, 仲里佑利奈

    日本天文学会年会講演予稿集   2023  2023年

    J-GLOBAL

  • 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   2022  2022年

    J-GLOBAL

  • 遠方銀河で観測された高い[O III]88μm/[C II]158μm光度比の原因-近傍銀河からの示唆

    浦遼太, 橋本拓也, 井上昭雄, 菅原雄馬, 札本佳伸, DARIO Fadda, 田村陽一, 萩本将都, 松尾宏, 馬渡健, 山中郷史, HAYES Matthew, PUSCHNIG Johannes, ZACKRISSON Erick

    日本天文学会年会講演予稿集   2022  2022年

    J-GLOBAL

  • SSASS領域(SSA22-HIT)における中性水素トモグラフィー調査(II):2.7<z<3.55でのトモグラフィーマップ

    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   2021  2021年

    J-GLOBAL

  • ALMAを用いた赤方偏移6にあるクェーサーの[OI]63μm輝線観測と星間媒質の性質の解明

    石井希実, 橋本拓也, 久野成夫, 保田敦司, 河原沙帆, 浦遼太, SALAK Dragan, 道山知成, 井上昭雄, 田村陽一, 松尾宏, 馬渡健

    日本天文学会年会講演予稿集   2021  2021年

    J-GLOBAL

  • 赤方偏移z=9.11[O III]輝線銀河のALMAサイクル6追観測

    徳岡剛史, 橋本拓也, 井上昭雄, 田村陽一, 松尾宏, 馬渡健, 山中郷史, 吉田直紀, 森脇可奈, 清水一紘

    日本天文学会年会講演予稿集   2020  2020年

    J-GLOBAL

  • [OIII]88μm,[CII]158μm,遠赤外線の光度を用いた赤方偏移z=8.312の銀河に対する星間物質の“porosity“の推定

    萩本将都, 田村陽一, BAKX Tom, 須永夏帆, 谷口暁星, 井上昭雄, 橋本拓也, 馬渡健, 播金優一, 松尾宏

    日本天文学会年会講演予稿集   2020  2020年

    J-GLOBAL

  • 遠赤外から紫外線データに基づくz=6.1のライマンブレイク銀河における電離状態の診断

    須永夏帆, 田村陽一, 谷口暁星, BAKX Tom, 馬渡健, 井上昭雄, 橋本拓也, 李民主, 松尾宏

    日本天文学会年会講演予稿集   2019  2019年

    J-GLOBAL

  • 原始超銀河団を包む中性水素ガス

    馬渡 健

    物理雑誌パリティ   33 ( 1月号 )  2018年01月  [招待有り]

    記事・総説・解説・論説等(商業誌、新聞、ウェブメディア)  

  • SSA22原始銀河団領域(SSA22-HIT)におけるHI(中性水素)トモグラフィーサーベイ(I):概要および初期結果

    馬渡健, 大塚拓也, 山田亨, 林野友紀, 井上昭雄, LEE Khee-Gan, 山中郷史, 柏川伸成, 松田有一, 岩田生, 田村陽一, 梅畑豪紀, SCHLEGEL David, PROCHASKA Xavier, TEJOS Nicolas, HENNAWEI Joe

    日本天文学会年会講演予稿集   2018  2018年

    J-GLOBAL

  • ALMAによるz=6.11ライマンブレイク銀河における[OIII]88μm輝線の検出

    須永夏帆, 田村陽一, 李民主, 馬渡健, 井上昭雄, 橋本拓也, 松尾宏

    日本天文学会年会講演予稿集   2018  2018年

    J-GLOBAL

  • "影絵"で見えた 115 億年前の宇宙の原始超銀河団ガス

    馬渡 健

    すばる望遠鏡ウェブリリース    2017年03月  [招待有り]

    記事・総説・解説・論説等(商業誌、新聞、ウェブメディア)  

  • ALMAによる赤方偏移z≒8.4のライマンブレイク銀河のダスト検出

    田村陽一, 竹内努, 井上昭雄, 橋本拓也, 馬渡健, 松尾宏, 松田有一, 清水一紘, 岡本崇, 吉田直紀, 澁谷隆俊, 河野孝太郎, 廿日出文洋, ZACKRISSON Erik, 谷口義明, 梅畑豪紀, 太田一陽

    日本天文学会年会講演予稿集   2017  2017年

    J-GLOBAL

  • 赤方偏移z=7.2ライマンα輝線銀河の遠赤外線[O III]88μm輝線の検出

    井上昭雄, 田村陽一, 松尾宏, 馬渡健, 清水一紘, 澁谷隆俊, 太田一陽, 吉田直紀, ZACKRISSON Erik, 柏川伸成, 河野孝太郎, 梅畑豪紀, 廿日出文洋, 家正則, 松田有一, 岡本崇, 山口裕貴

    日本天文学会年会講演予稿集   2016  2016年

    J-GLOBAL

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現在担当している科目

▼全件表示

担当経験のある科目(授業)

  • 物理学1

    大阪産業大学  

  • 基礎物理学および演習

    大阪産業大学  

 

社会貢献活動

  • もしも君が杜の都で天文学者になったら。。。

    東北大学天文学専攻 

    2012年08月
     
     

  • 仙台市天文台天文台祭り

    仙台市天文台 

    2012年02月
     
     

  • もしも君が杜の都で天文学者になったら。。。

    2011年09月
    -
    2011年10月

  • 科学者の卵養成講座「君が天文学者になる4日間」

    東北大学天文学専攻 

    2011年09月
     
     

他学部・他研究科等兼任情報

  • 理工学術院   先進理工学部