2024/06/17 更新

写真a

スガハラ ユウマ
菅原 悠馬
所属
理工学術院 先進理工学部
職名
講師(任期付)

学歴

  • 2017年04月
    -
    2020年03月

    東京大学   大学院理学系研究科   物理学専攻  

  • 2015年04月
    -
    2017年03月

    東京大学   大学院理学系研究科   物理学専攻  

  • 2011年04月
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    2015年03月

    京都大学   理学部   理学科  

研究分野

  • 天文学   系外銀河天文学
 

論文

  • EMPRESS. XIV. Strong High-ionization Lines of Young Galaxies at z = 0-8: Ionizing Spectra Consistent with the Intermediate-mass Black Holes with M <inf>BH</inf> ∼ 103-106 M <inf>⊙</inf>

    Shun Hatano, Masami Ouchi, Hiroya Umeda, Kimihiko Nakajima, Toshihiro Kawaguchi, Yuki Isobe, Shohei Aoyama, Kuria Watanabe, Yuichi Harikane, Haruka Kusakabe, Akinori Matsumoto, Takashi J. Moriya, Moka Nishigaki, Yoshiaki Ono, Masato Onodera, Yuma Sugahara, Akihiro Suzuki, Yi Xu, Yechi Zhang

    Astrophysical Journal   966 ( 2 )  2024年05月

     概要を見る

    We present ionizing spectra estimated at 13.6-100 eV for 10 dwarf galaxies with strong high-ionization lines of He ii λ4686 and [Ne v] λ3426 ([Ne iv] λ2424) at z = 0 (z = 8) that are identified in our Keck/LRIS spectroscopy and the literature (the JWST Early Release Observations program). With the flux ratios of these high-ionization lines and >10 low-ionization lines of hydrogen, helium, oxygen, neon, and sulfur, we determine ionizing spectra consisting of stellar and nonthermal power-law radiation by photoionization modeling with free parameters of nebular properties, including metallicity and ionization parameter, canceling out abundance ratio differences. We find that all of the observed flux ratios are well reproduced by the photoionization models with the power-law index α EUV of α EUV ∼ (-1) − 0 and the luminosity L EUV of L EUV ∼ 1040-1042 erg s−1 at ∼55-100 eV for six galaxies, while four galaxies include large systematics in α EUV caused by stellar radiation contamination. We then compare α EUV and L EUV of these six galaxies with those predicted by the black hole (BH) accretion disk models and find that α EUV and L EUV are similar to those of the intermediate-mass BHs (IMBHs) in BH accretion disk models, albeit with possibilities of the other scenarios. Confirming these results with a known IMBH having a mass M BH of M BH = 105.75 M ⊙, we find that four local galaxies and one z = 7.665 galaxy have ionizing spectra consistent with those of IMBHs with M BH ∼ 103-105 M ⊙

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  • JWST and ALMA Multiple-line Study in and around a Galaxy at z = 8.496: Optical to Far-Infrared Line Ratios and the Onset of an Outflow Promoting Ionizing Photon Escape

    Seiji Fujimoto, Masami Ouchi, Kimihiko Nakajima, Yuichi Harikane, Yuki Isobe, Gabriel Brammer, Masamune Oguri, Clara Giménez-Arteaga, Kasper E. Heintz, Vasily Kokorev, Franz E. Bauer, Andrea Ferrara, Takashi Kojima, Claudia del P. Lagos, Sommovigo Laura, Daniel Schaerer, Kazuhiro Shimasaku, Bunyo Hatsukade, Kotaro Kohno, Fengwu Sun, Francesco Valentino, Darach Watson, Yoshinobu Fudamoto, Akio K. Inoue, Jorge González-López, Anton M. Koekemoer, Kirsten Knudsen, Minju M. Lee, Georgios E. Magdis, Johan Richard, Victoria B. Strait, Yuma Sugahara, Yoichi Tamura, Sune Toft, Hideki Umehata, Gregory Walth

    The Astrophysical Journal    2024年04月

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  • EMPRESS. XIII. Chemical Enrichment of Young Galaxies Near and Far at z ∼ 0 and 4–10: Fe/O, Ar/O, S/O, and N/O Measurements with a Comparison of Chemical Evolution Models

    Kuria Watanabe, Masami Ouchi, Kimihiko Nakajima, Yuki Isobe, Nozomu Tominaga, Akihiro Suzuki, Miho N. Ishigaki, Ken’ichi Nomoto, Koh Takahashi, Yuichi Harikane, Shun Hatano, Haruka Kusakabe, Takashi J. Moriya, Moka Nishigaki, Yoshiaki Ono, Masato Onodera, Yuma Sugahara

    The Astrophysical Journal    2024年02月

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  • Molecular Outflow in the Reionization-epoch Quasar J2054-0005 Revealed by OH 119 μm Observations

    Dragan Salak, Takuya Hashimoto, Akio K. Inoue, Tom J. L. C. Bakx, Darko Donevski, Yoichi Tamura, Yuma Sugahara, Nario Kuno, Yusuke Miyamoto, Seiji Fujimoto, Suphakorn Suphapolthaworn

    The Astrophysical Journal    2024年02月

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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.

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  • Big Three Dragons: Molecular Gas in a Bright Lyman-break Galaxy at z = 7.15

    Takuya Hashimoto, Akio K. Inoue, Yuma Sugahara, Yoshinobu Fudamoto, Seiji Fujimoto, K. K. Knudsen, Hiroshi Matsuo, Yoichi Tamura, Satoshi Yamanaka, Yuichi Harikane, Nario Kuno, Yoshiaki Ono, Dragan Salak, Nozomi Ishii

    Astrophysical Journal   952 ( 1 )  2023年07月

     概要を見る

    We report Atacama Large Millimeter/submillimeter Array Band 3 observations of CO(6−5), CO(7−6), and [C i](2−1) in B14-65666 (“Big Three Dragons”), one of the brightest Lyman-break galaxies at z > 7 in the rest-frame ultraviolet continuum, far-infrared continuum, and emission lines of [O iii] 88 μm and [C ii] 158 μm. CO(6−5), CO(7−6), and [C i](2−1), whose 3σ upper limits on the luminosities are approximately 40 times fainter than the [C ii] luminosity, are all not detected. The L [C II]/L CO(6-5) and L [C II]/L CO(7-6) ratios are higher than the typical ratios obtained in dusty star-forming galaxies or quasar host galaxies at similar redshifts, and they may suggest a lower gas density in the photodissociated region in B14-65666. By using the (1) [C ii] luminosity, (2) dust mass-to-gas mass ratio, and (3) a dynamical mass estimate, we find that the molecular gas mass (M mol) is (0.05-11) × 1010 M ⊙. This value is consistent with the upper limit inferred from the nondetection of mid-J CO and [C i](2−1). Despite the large uncertainty in M mol, we estimate a molecular gas-to-stellar mass ratio (μ gas) of 0.65-140 and a gas depletion time (τ dep) of 2.5-550 Myr; these values are broadly consistent with those of other high-redshift galaxies. B14-65666 could be an ancestor of a passive galaxy at z ≳ 4 if no gas is fueled from outside the galaxy.

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  • 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

    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   952 ( 1 )  2023年07月  [査読有り]

     概要を見る

    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.

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  • EMPRESS. IX. Extremely Metal-poor Galaxies are Very Gas-rich Dispersion-dominated Systems: Will the James Webb Space Telescope Witness Gaseous Turbulent High-z Primordial Galaxies?

    Yuki Isobe, Masami Ouchi, Kimihiko Nakajima, Shinobu Ozaki, Nicolas F. Bouché, John H. Wise, Yi Xu, Eric Emsellem, Haruka Kusakabe, Takashi Hattori, Tohru Nagao, Gen Chiaki, Hajime Fukushima, Yuichi Harikane, Kohei Hayashi, Yutaka Hirai, Ji Hoon Kim, Michael V. Maseda, Kentaro Nagamine, Takatoshi Shibuya, Yuma Sugahara, Hidenobu Yajima, Shohei Aoyama, Seiji Fujimoto, Keita Fukushima, Shun Hatano, Akio K. Inoue, Tsuyoshi Ishigaki, Masahiro Kawasaki, Takashi Kojima, Yutaka Komiyama, Shuhei Koyama, Yusei Koyama, Chien-Hsiu Lee, Akinori Matsumoto, Ken Mawatari, Takashi J. Moriya, Kentaro Motohara, Kai Murai, Moka Nishigaki, Masato Onodera, Yoshiaki Ono, Michael Rauch, Tomoki Saito, Rin Sasaki, Akihiro Suzuki, Tsutomu T. Takeuchi, Hiroya Umeda, Masayuki Umemura, Kuria Watanabe, Kiyoto Yabe, Yechi Zhang

    The Astrophysical Journal   951 ( 2 ) 102 - 102  2023年07月  [査読有り]

     概要を見る

    Abstract

    We present kinematics of six local extremely metal-poor galaxies (EMPGs) with low metallicities (0.016–0.098 Z) and low stellar masses (104.7–107.6M). Taking deep medium/high-resolution (R ∼ 7500) integral-field spectra with 8.2 m Subaru, we resolve the small inner velocity gradients and dispersions of the EMPGs with Hα emission. Carefully masking out substructures originating by inflow and/or outflow, we fit three-dimensional disk models to the observed Hα flux, velocity, and velocity dispersion maps. All the EMPGs show rotational velocities (vrot) of 5–23 km s−1 smaller than the velocity dispersions (σ0) of 17–31 km s−1, indicating dispersion-dominated (vrot0 = 0.29–0.80 &lt; 1) systems affected by inflow and/or outflow. Except for two EMPGs with large uncertainties, we find that the EMPGs have very large gas-mass fractions of fgas ≃ 0.9–1.0. Comparing our results with other Hα kinematics studies, we find that vrot0 decreases and fgas increases with decreasing metallicity, decreasing stellar mass, and increasing specific star formation rate. We also find that simulated high-z (z ∼ 7) forming galaxies have gas fractions and dynamics similar to the observed EMPGs. Our EMPG observations and the simulations suggest that primordial galaxies are gas-rich dispersion-dominated systems, which would be identified by the forthcoming James Webb Space Telescope observations at z ∼ 7.

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  • Revisiting the Dragonfly galaxy – I. High-resolution ALMA and VLA observations of the radio hotspots in a hyper-luminous infrared galaxy at z = 1.92

    Yuxing Zhong, Akio K Inoue, Yuma Sugahara, Kana Morokuma-Matsui, Shinya Komugi, Hiroyuki Kaneko, Yoshinobu Fudamoto

    Monthly Notices of the Royal Astronomical Society   522 ( 4 ) 6123 - 6136  2023年05月

     概要を見る

    ABSTRACT

    Radio-loud active galactic nuclei (RLAGNs) are rare among AGN populations. Lacking high-resolution and high-frequency observations, their structure and evolution stages are not well understood at high redshifts. In this work, we report Atacama Large Millimeter/submillimeter Array 237 GHz continuum observation at 0.023 arcsec resolution and Very Large Array (VLA) 44 GHz continuum observation at 0.08 arcsec resolution of the radio continuum emission from a high-redshift radio and hyper-luminous infrared galaxy at z = 1.92. The new observations confirm the South-East (SE) and North-West (NW) hotspots identified by previous low-resolution VLA observations at 4.7 and 8.2 GHz and identify a radio core undetected in all previous observations. The SE hotspot has a higher flux density than the NW one does by a factor of 6, suggesting that there can be a Doppler boosting effect in the SE one. In this scenario, we estimate the advance speed of the jet head, ranging from ∼0.1c to 0.3c, which yields a mildly relativistic case. The projected linear distance between the two hotspots is ∼13 kpc, yielding a linear size (≤20 kpc) of a compact-steep-spectrum (CSS) source. Combined with new high-frequency (νobs ≥ 44 GHz) and archived low-frequency observations (νobs ≤ 8.2 GHz), we find that injection spectra of both NW and SE hotspots can be fitted with a continuous injection (CI) model. Based on the CI model, the synchrotron ages of NW and SE hotspots have an order of 105 yr, consistent with the order of magnitude 103–105 yr observed in CSS sources associated with radio AGNs at an early evolution stage. The CI model also favours the scenario in which the double hotspots have experienced a quiescent phase, suggesting that this RLAGN may have transient or intermittent activities.

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

    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   945   69  2023年03月  [査読有り]

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  • Identification of large equivalent width dusty galaxies at 4 &lt; z &lt; 6 from sub-millimetre colours

    Burgarella, D., Theul{\'e}, P., Buat, V., Gouiran, L., Turco, L., Boquien, M., Bakx, T.J.L.C., Inoue, A.K., Fudamoto, Y., Sugahara, Y., Zavala, J.

    Astronomy and Astrophysics   671  2023年

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  • CLASSY. VI. The Density, Structure, and Size of Absorption-line Outflows in Starburst Galaxies

    Xu, X., Heckman, T., Henry, A., Berg, D.A., Chisholm, J., James, B.L., Martin, C.L., Stark, D.P., Hayes, M., Arellano-C{\'o}rdova, K.Z., Carr, C., Huberty, M., Mingozzi, M., Scarlata, C., Sugahara, Y.

    Astrophysical Journal   948 ( 1 )  2023年

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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* * Based on observations done with FIFI-LS on SOFIA.

    Ura, R., Hashimoto, T., Inoue, A.K., Fadda, D., Hayes, M., Puschnig, J., Zackrisson, E., Tamura, Y., Matsuo, H., Mawatari, K., Fudamoto, Y., Hagimoto, M., Kuno, N., Sugahara, Y., Yamanaka, S., C. Bakx, T.J.L., Nakazato, Y., Usui, M., Yajima, H., Yoshida, N.

    Astrophysical Journal   948 ( 1 )  2023年

     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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  • Estimating dust temperature and Far-IR luminosity of high-redshift galaxies using ALMA single-band continuum observations

    Fudamoto, Y., Inoue, A.K., Sugahara, Y.

    Monthly Notices of the Royal Astronomical Society   521 ( 2 )  2023年

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  • EMPRESS. VIII. A New Determination of Primordial He Abundance with Extremely Metal-poor Galaxies: A Suggestion of the Lepton Asymmetry and Implications for the Hubble Tension

    Akinori Matsumoto, Masami Ouchi, Kimihiko Nakajima, Masahiro Kawasaki, Kai Murai, Kentaro Motohara, Yuichi Harikane, Yoshiaki Ono, Kosuke Kushibiki, Shuhei Koyama, Shohei Aoyama, Masahiro Konishi, Hidenori Takahashi, Yuki Isobe, Hiroya Umeda, Yuma Sugahara, Masato Onodera, Kentaro Nagamine, Haruka Kusakabe, Yutaka Hirai, Takashi J. Moriya, Takatoshi Shibuya, Yutaka Komiyama, Keita Fukushima, Seiji Fujimoto, Takashi Hattori, Kohei Hayashi, Akio K. Inoue, Shotaro Kikuchihara, Takashi Kojima, Yusei Koyama, Chien-Hsiu Lee, Ken Mawatari, Takashi Miyata, Tohru Nagao, Shinobu Ozaki, Michael Rauch, Tomoki Saito, Akihiro Suzuki, Tsutomu T. Takeuchi, Masayuki Umemura, Yi Xu, Kiyoto Yabe, Yechi Zhang, Yuzuru Yoshii

    The Astrophysical Journal   941 ( 2 ) 167 - 167  2022年12月

     概要を見る

    Abstract

    The primordial He abundance YP is a powerful probe of cosmology. Currently, YP is best determined by observations of metal-poor galaxies, while there are only a few known local extremely metal-poor (&lt;0.1Z) galaxies (EMPGs) having reliable He/H measurements with He iλ10830 near-infrared (NIR) emission. Here we present deep Subaru NIR spectroscopy for 10 EMPGs. Combining the existing optical data, He/H values of 5 out of the 10 EMPGs are reliably derived by the Markov chain Monte Carlo algorithm. Adding the existing 3 EMPGs and 51 moderately metal-poor (0.1–0.4Z) galaxies with reliable He/H estimates, we obtain ${Y}_{ { \rm{P } } }={0.2370}_{-0.0034}^{+0.0033}$ by linear regression in the (He/H) − (O/H) plane, where we increase the number of EMPGs from three to eight anchoring He/H of the most metal-poor gas in galaxies. Although our YP measurement and previous measurements are consistent, our result is slightly (∼1σ) smaller due to our EMPGs. Including the existing primordial deuterium DP measurement, we constrain the effective number of neutrino species Neff and the baryon-to-photon ratio η showing ≳1–2σ tensions with the Standard Model and Planck Collaboration et al. (2020). Motivated by the tensions, we allow the degeneracy parameter of the electron neutrino ξe, as well as Neff and η, to vary. We obtain ${\xi }_{e}={0.05}_{-0.02}^{+0.03}$, ${N}_{\mathrm{eff } }={3.11}_{-0.31}^{+0.34}$, and $\eta \times {10}^{10}={6.08}_{-0.06}^{+0.06}$ from the YP and DP measurements with a prior of η taken from Planck Collaboration et al. Our constraints suggest a lepton asymmetry and allow for a high value of Neff within the 1σ level, which could mitigate the Hubble tension.

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  • ALMA Observations of CO Emission from Luminous Lyman-break Galaxies at z = 6.0293–6.2037

    Yoshiaki Ono, Seiji Fujimoto, Yuichi Harikane, Masami Ouchi, Livia Vallini, Andrea Ferrara, Takatoshi Shibuya, Andrea Pallottini, Akio K. Inoue, Masatoshi Imanishi, Kazuhiro Shimasaku, Takuya Hashimoto, Chien-Hsiu Lee, Yuma Sugahara, Yoichi Tamura, Kotaro Kohno, Malte Schramm

    The Astrophysical Journal   941 ( 1 ) 74 - 74  2022年12月

     概要を見る

    Abstract

    We present our new Atacama Large Millimeter/submillimeter Array (ALMA) observations targeting CO(6–5) emission from three luminous Lyman-break galaxies (LBGs) at zspec = 6.0293–6.2037 found in the Subaru/Hyper Suprime-Cam survey, whose [O iii] 88 μm and [C ii] 158 μm emissions have been detected with ALMA. We find a marginal detection of the CO(6–5) line from one of our LBGs, J0235–0532, at the ≃4σ significance level and obtain upper limits for the other two LBGs, J1211–0118 and J0217–0208. Our z = 6 luminous LBGs are consistent with the previously found correlation between the CO luminosity and the infrared luminosity. The unique ensemble of the multiple far-infrared emission lines and underlying continuum fed to a photodissociation region model reveals that J0235–0532 has a relatively high density of hydrogen nuclei nH that is comparable to those of low-z (U)LIRGs, quasars, and Galactic star-forming regions with high nH values, while the other two LBGs have lower nH consistent with local star-forming galaxies. By carefully taking account of various uncertainties, we obtain constraints on total gas mass and gas surface density from their CO luminosity measurements. We find that J0235–0532 is located below the Kennicutt–Schmidt (KS) relation, comparable to the z = 5.7 LBG, HZ10, previously detected with CO(2–1). Combined with previous results for dusty starbursts at similar redshifts, the KS relation at z = 5–6 is on average consistent with the local one.

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  • EMPRESS. V. Metallicity Diagnostics of Galaxies over 12 + log(O/H) ≃ 6.9–8.9 Established by a Local Galaxy Census: Preparing for JWST Spectroscopy

    Kimihiko Nakajima, Masami Ouchi, Yi Xu, Michael Rauch, Yuichi Harikane, Moka Nishigaki, Yuki Isobe, Haruka Kusakabe, Tohru Nagao, Yoshiaki Ono, Masato Onodera, Yuma Sugahara, Ji Hoon Kim, Yutaka Komiyama, Chien-Hsiu Lee, Fakhri S. Zahedy

    The Astrophysical Journal Supplement Series   262 ( 1 ) 3 - 3  2022年09月

     概要を見る

    Abstract

    We present optical-line gas metallicity diagnostics established by the combination of local SDSS galaxies and the largest compilation of extremely metal-poor galaxies (EMPGs) including new EMPGs identified by the Subaru EMPRESS survey. A total of 103 EMPGs are included, covering a large parameter space of magnitude (Mi = −19 to −7) and Hβ equivalent width (10–600 Å), i.e., wide ranges of stellar mass and star formation rate. Using reliable metallicity measurements from the direct method for these galaxies, we derive the relationships between strong optical-line ratios and gas-phase metallicity over the range of $12+\mathrm{log}({\rm{O } }/{\rm{H } })$ ≃ 6.9–8.9, corresponding to 0.02–2 solar metallicity Z. We confirm that the R23 index, ([O iii]+[O ii])/Hβ, is the most accurate metallicity indicator with a metallicity uncertainty of 0.14 dex over the range among various popular metallicity indicators. The other metallicity indicators show large scatters in the metal-poor range (≲0.1 Z). It is explained by our CLOUDY photoionization modeling that, unlike the R23 index, the other metallicity indicators do not use a sum of singly and doubly ionized lines and cannot trace both low- and high-ionization gas. We find that the accuracy of the metallicity indicators is significantly improved if one uses Hβ equivalent width measurements that tightly correlate with ionization states. In this work, we also present the relation of physical properties with the UV-continuum slope β and ionization production rate ξion derived with GALEX data for the EMPGs and provide local anchors of galaxy properties together with the optical-line metallicity indicators that are available in the form of a machine-readable table and useful for forthcoming JWST spectroscopic studies.

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  • Bridging Optical and Far-infrared Emission-line Diagrams of Galaxies from Local to the Epoch of Reionization: Characteristic High [O iii] 88 μm/SFR at z &gt; 6

    Yuma Sugahara, Akio K. Inoue, Yoshinobu Fudamoto, Takuya Hashimoto, Yuichi Harikane, Satoshi Yamanaka

    The Astrophysical Journal   935 ( 2 ) 119 - 119  2022年08月

     概要を見る

    Abstract

    We present photoionization modeling of galaxy populations at z ∼ 0, 2, and &gt;6 to bridge optical and far-infrared (FIR) emission-line diagrams. We collect galaxies with measurements of optical and/or FIR ([O iii] 88 μm and [C ii] 158 μm) emission-line fluxes and plot them on the [O iii]λ5007/Hβ–[N ii]λ6585/Hα (BPT) and L([O iii]88)/SFR–L([C ii]158)/SFR diagrams, where SFR is the star formation rate and L([O iii]88) and L([C ii]158) are the FIR line luminosities. We aim to explain the galaxy distributions on the two diagrams with photoionization models that employ three nebular parameters: the ionization parameter U, hydrogen density nH, and gaseous metallicity Zgas. Our models successfully reproduce the nebular parameters of local galaxies, and then predict the distributions of the z ∼ 0, 2, and &gt;6 galaxies in the diagrams. The predicted distributions illustrate the redshift evolution on all the diagrams; e.g., [O iii]/Hβ and [O iii]88/[C ii]158 ratios continuously decrease from z &gt; 6 to 0. Specifically, the z &gt; 6 galaxies exhibit ∼0.5 dex higher U than low-redshift galaxies at a given Zgas and show predicted flat distributions on the BPT diagram at ${\rm{log } }[{\rm{O } }\,{\rm\small{III } }]/{\rm{H } }\beta \,=\,$ 0.5–0.8. We find that some of the z &gt; 6 galaxies exhibit high L([O iii]88)/SFR ratios. To explain these high ratios, our photoionization models require a low stellar-to-gaseous-metallicity ratio or bursty/increasing star formation history at z &gt; 6. JWST will test the predictions and scenarios for the z &gt; 6 galaxies proposed by our photoionization modeling.

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  • Possible Systematic Rotation in the Mature Stellar Population of a z = 9.1 Galaxy

    Tsuyoshi Tokuoka, Akio K. Inoue, Takuya Hashimoto, Richard S. Ellis, Nicolas Laporte, Yuma Sugahara, Hiroshi Matsuo, Yoichi Tamura, Yoshinobu Fudamoto, Kana Moriwaki, Guido Roberts-Borsani, Ikkoh Shimizu, Satoshi Yamanaka, Naoki Yoshida, Erik Zackrisson, Wei Zheng

    Astrophysical Journal Letters   933 ( 1 )  2022年07月

     概要を見る

    We present new observations with the Atacama Large Millimeter/submillimeter Array for a gravitationally lensed galaxy at z = 9.1, MACS1149-JD1. [O iii] 88 μm emission is detected at 10σ with a spatial resolution of 1/40.3 kpc in the source plane, enabling the most distant morphokinematic study of a galaxy. The [O iii] emission is distributed smoothly without any resolved clumps and shows a clear velocity gradient with "V obs/2σ tot = 0.84 ± 0.23, where "V obs is the observed maximum velocity difference and σ tot is the velocity dispersion measured in the spatially integrated line profile, suggesting a rotating system. Assuming a geometrically thin self-gravitating rotation disk model, we obtain Vrot/σV=0.67-0.26+0.73, where V rot and σ V are the rotation velocity and velocity dispersion, respectively, still consistent with rotation. The resulting disk mass of 0.65-0.40+1.37×109 M ⊙ is consistent with being associated with the stellar mass identified with a 300 Myr old stellar population independently indicated by a Balmer break in the spectral energy distribution. We conclude that the most of the dynamical mass is associated with the previously identified mature stellar population that formed at z ∼15.

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    9
    被引用数
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  • EMPRESS. VI. Outflows Investigated in Low-mass Galaxies with M ∗ = 104–107 M ⊙: Weak Feedback in Low-mass Galaxies?

    Yi Xu, Masami Ouchi, Michael Rauch, Kimihiko Nakajima, Yuichi Harikane, Yuma Sugahara, Yutaka Komiyama, Haruka Kusakabe, Seiji Fujimoto, Yuki Isobe, Ji Hoon Kim, Yoshiaki Ono, Fakhri S. Zahedy

    The Astrophysical Journal    2022年04月

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    11
    被引用数
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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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    被引用数
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  • EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M * = 104–105 M and 2%–3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae

    Yuki Isobe, Masami Ouchi, Akihiro Suzuki, Takashi J. Moriya, Kimihiko Nakajima, Ken’ichi Nomoto, Michael Rauch, Yuichi Harikane, Takashi Kojima, Yoshiaki Ono, Seiji Fujimoto, Akio K. Inoue, Ji Hoon Kim, Yutaka Komiyama, Haruka Kusakabe, Chien-Hsiu Lee, Michael Maseda, Jorryt Matthee, Leo Michel-Dansac, Tohru Nagao, Themiya Nanayakkara, Moka Nishigaki, Masato Onodera, Yuma Sugahara, Yi Xu

    The Astrophysical Journal   925 ( 2 ) 111 - 111  2022年02月

     概要を見る

    Abstract

    We present Keck/LRIS follow-up spectroscopy for 13 photometric candidates of extremely metal-poor galaxies (EMPGs) selected by a machine-learning technique applied to the deep (∼26 AB mag) optical and wide-area (∼500 deg2) Subaru imaging data in the EMPRESS survey. Nine out of the 13 candidates are EMPGs with an oxygen abundance (O/H) less than ∼10% solar value (O/H), and four sources are contaminants of moderately metal-rich galaxies or no emission-line objects. Notably, two out of the nine EMPGs have extremely low stellar masses and oxygen abundances of 5 × 104–7 × 105M and 2%–3% (O/H), respectively. With a sample of five EMPGs with (Fe/O) measurements, two (three) of which are taken from this study (the literature), we confirm that two EMPGs with the lowest (O/H) ratios of ∼2% (O/H) show high (Fe/O) ratios of ∼0.1, close to the solar abundance ratio. Comparing galaxy chemical enrichment models, we find that the two EMPGs cannot be explained by a scenario of metal-poor gas accretion/episodic star formation history due to their low (N/O) ratios. We conclude that the two EMPGs can be reproduced by the inclusion of bright hypernovae and/or hypothetical pair-instability supernovae (SNe) preferentially produced in a metal-poor environment. This conclusion implies that primordial galaxies at z ∼ 10 could have a high abundance of Fe that did not originate from Type Ia SNe with delays and that Fe may not serve as a cosmic clock for primordial galaxies.

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    19
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  • CLASSY III. the Properties of Starburst-driven Warm Ionized Outflows

    Xu, X., Heckman, T., Henry, A., Berg, D.A., Chisholm, J., James, B.L., Martin, C.L., Stark, D.P., Aloisi, A., Amor{\'i}n, R.O., Arellano-C{\'o}rdova, K.Z., Bordoloi, R., Charlot, S., Chen, Z., Hayes, M., Mingozzi, M., Sugahara, Y., Kewley, L.J., Ouchi, M., Scarlata, C., Steidel, C.C.

    Astrophysical Journal   933 ( 2 )  2022年

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    33
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  • CLASSY IV. Exploring UV Diagnostics of the Interstellar Medium in Local High-z Analogs at the Dawn of the JWST Era

    Mingozzi, M., James, B.L., Arellano-C{\'o}rdova, K.Z., Berg, D.A., Senchyna, P., Chisholm, J., Brinchmann, J., Aloisi, A., Amor{\'i}n, R.O., Charlot, S., Feltre, A., Hayes, M., Heckman, T., Henry, A., Hern, ez, S., Kumari, N., Leitherer, C., Llerena, M., Martin, C.L., Nanayakkara, T., Ravindranath, S., Skillman, E.D., Sugahara, Y., Wofford, A., Xu, X.

    Astrophysical Journal   939 ( 2 )  2022年

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    22
    被引用数
    (Scopus)
  • CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey

    James, B.L., Berg, D.A., King, T., Sahnow, D.J., Mingozzi, M., Chisholm, J., Heckman, T., Martin, C.L., Stark, D.P., Aloisi, A., Amor{\'i}n, R.O., Arellano-C{\'o}rdova, K.Z., Bayliss, M., Bordoloi, R., Brinchmann, J., Charlot, S., Chen, Z., Chevallard, J., Clark, I., Erb, D.K., Feltre, A., Hayes, M., Henry, A., Hern, ez, S., Jaskot, A., Kewley, L.J., Kumari, N., Leitherer, C., Llerena, M., Maseda, M., Nanayakkara, T., Ouchi, M., Plat, A., Pogge, R.W., Ravindranath, S., Rigby, J.R., Scarlata, C., Senchyna, P., Skillman, E.D., Steidel, C.C., Strom, A.L., Sugahara, Y., Wilkins, S.M., Wofford, A., Xu, X.

    Astrophysical Journal, Supplement Series   262 ( 2 )  2022年

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    11
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  • Big Three Dragons: A [N ii] 122 μm Constraint and New Dust-continuum Detection of a z = 7.15 Bright Lyman-break Galaxy with ALMA

    Yuma Sugahara, Akio K. Inoue, Takuya Hashimoto, Satoshi Yamanaka, Seiji Fujimoto, Yoichi Tamura, Hiroshi Matsuo, Christian Binggeli, Erik Zackrisson

    The Astrophysical Journal   923 ( 1 ) 5 - 5  2021年12月

     概要を見る

    <title>Abstract</title>
    We present new Atacama Large Millimeter/submillimeter Array Band 7 observational results of a Lyman-break galaxy at <italic>z</italic> = 7.15, B14-65666 (“Big Three Dragons”), which is an object detected in [O <sc>iii</sc>] 88 <italic>μ</italic>m, [C <sc>ii</sc>] 158 <italic>μ</italic>m, and dust continuum emission during the epoch of reionization. Our targets are the [N <sc>ii</sc>] 122 <italic>μ</italic>m fine-structure emission line and the underlying 120 <italic>μ</italic>m dust continuum. The dust continuum is detected with a ∼19<italic>σ</italic> significance. From far-infrared spectral energy distribution sampled at 90, 120, and 160 <italic>μ</italic>m, we obtain a best-fit dust temperature of 40 K (79 K) and an infrared luminosity of <inline-formula>
    <tex-math>
    <?CDATA ${\mathrm{log } }_{10}({L}_{\mathrm{IR } }/{L}_{\odot })=11.6$?>
    </tex-math>
    <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
    <mml:msub>
    <mml:mrow>
    <mml:mi>log</mml:mi>
    </mml:mrow>
    <mml:mrow>
    <mml:mn>10</mml:mn>
    </mml:mrow>
    </mml:msub>
    <mml:mo stretchy="false">(</mml:mo>
    <mml:msub>
    <mml:mrow>
    <mml:mi>L</mml:mi>
    </mml:mrow>
    <mml:mrow>
    <mml:mi>IR</mml:mi>
    </mml:mrow>
    </mml:msub>
    <mml:mrow>
    <mml:mo stretchy="true">/</mml:mo>
    </mml:mrow>
    <mml:msub>
    <mml:mrow>
    <mml:mi>L</mml:mi>
    </mml:mrow>
    <mml:mrow>
    <mml:mo>⊙</mml:mo>
    </mml:mrow>
    </mml:msub>
    <mml:mo stretchy="false">)</mml:mo>
    <mml:mo>=</mml:mo>
    <mml:mn>11.6</mml:mn>
    </mml:math>
    <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2a36ieqn1.gif" xlink:type="simple" />
    </inline-formula> (12.1) at the emissivity index <italic>β</italic> = 2.0 (1.0). The [N <sc>ii</sc>] 122 <italic>μ</italic>m line is not detected. The 3<italic>σ</italic> upper limit of the [N <sc>ii</sc>] luminosity is 8.1 × 107
    <italic>L</italic>
    . From the [N <sc>ii</sc>], [O <sc>iii</sc>], and [C <sc>ii</sc>] line luminosities, we use the Cloudy photoionization code to estimate nebular parameters as functions of metallicity. If the metallicity of the galaxy is high (<italic>Z</italic> &gt; 0.4 <italic>Z</italic>
    ), the ionization parameter and hydrogen density are <inline-formula>
    <tex-math>
    <?CDATA ${\mathrm{log } }_{10}U\simeq -2.7\pm 0.1$?>
    </tex-math>
    <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
    <mml:msub>
    <mml:mrow>
    <mml:mi>log</mml:mi>
    </mml:mrow>
    <mml:mrow>
    <mml:mn>10</mml:mn>
    </mml:mrow>
    </mml:msub>
    <mml:mi>U</mml:mi>
    <mml:mo>≃</mml:mo>
    <mml:mo>−</mml:mo>
    <mml:mn>2.7</mml:mn>
    <mml:mo>±</mml:mo>
    <mml:mn>0.1</mml:mn>
    </mml:math>
    <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2a36ieqn2.gif" xlink:type="simple" />
    </inline-formula> and <italic>n</italic>
    H ≃ 50–250 cm−3, respectively, which are comparable to those measured in low-redshift galaxies. The nitrogen-to-oxygen abundance ratio, N/O, is constrained to be subsolar. At <italic>Z</italic> &lt; 0.4 <italic>Z</italic>
    , the allowed <italic>U</italic> drastically increases as the assumed metallicity decreases. For high ionization parameters, the N/O constraint becomes weak. Finally, our Cloudy models predict the location of B14-65666 on the BPT diagram, thereby allowing a comparison with low-redshift galaxies.

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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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  • EMPRESS. II. Highly Fe-enriched Metal-poor Galaxies with ∼1.0 (Fe/O)⊙ and 0.02 (O/H)⊙: Possible Traces of Supermassive (>300 M ⊙) Stars in Early Galaxies* † ‡

    Takashi Kojima, Masami Ouchi, Michael Rauch, Yoshiaki Ono, Kimihiko Nakajima, Yuki Isobe, Seiji Fujimoto, Yuichi Harikane, Takuya Hashimoto, Masao Hayashi, Yutaka Komiyama, Haruka Kusakabe, Ji Hoon Kim, Chien-Hsiu Lee, Shiro Mukae, Tohru Nagao, Masato Onodera, Takatoshi Shibuya, Yuma Sugahara, Masayuki Umemura, Kiyoto Yabe

    The Astrophysical Journal   913 ( 1 ) 22 - 22  2021年05月

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    17
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  • Extremely Metal-poor Representatives Explored by the Subaru Survey (EMPRESS). I. A Successful Machine-learning Selection of Metal-poor Galaxies and the Discovery of a Galaxy with M* < 106 M ⊙ and 0.016 Z ⊙

    Takashi Kojima, Masami Ouchi, Michael Rauch, Yoshiaki Ono, Kimihiko Nakajima, Yuki Isobe, Seiji Fujimoto, Yuichi Harikane, Takuya Hashimoto, Masao Hayashi, Yutaka Komiyama, Haruka Kusakabe, Ji Hoon Kim, Chien-Hsiu Lee, Shiro Mukae, Tohru Nagao, Masato Onodera, Takatoshi Shibuya, Yuma Sugahara, Masayuki Umemura, Kiyoto Yabe

    The Astrophysical Journal   898 ( 2 ) 142 - 142  2020年08月

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    47
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  • Three-dimensional Distribution Map of Hi Gas and Galaxies around an Enormous Lyα 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, Yoshiaki Ono, 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, Takatoshi Shibuya, Yuichi Harikane, Seiji Fujimoto, Yi Kuan Chiang, Haibin Zhang, Ryota Kakuma

    Astrophysical Journal   896 ( 1 )  2020年06月

     概要を見る

    We present an IGM H i tomographic map in a survey volume of 16 × 19 × 131 h-3 commoving Mpc3 (cMpc3) centered at MAMMOTH-1 nebula and three neighboring quasars at z = 2.3. The MAMMOTH-1 nebula is an enormous Lyα nebula (ELAN), hosted by a type-II quasar dubbed MAMMOTH1-QSO, that extends over 1 h-1 cMpc with no clear physical origin. Here we investigate the H i-gas distribution around MAMMOTH1-QSO with the ELAN and three neighboring type-I quasars, making the IGM H i tomographic map with a spatial resolution of 2.6 h -1 cMpc. Our H i tomographic map is reconstructed with H i Lyα forest absorption of bright background objects at z = 2.4-2.9: one eBOSS quasar and 16 Keck/LRIS galaxy spectra. We estimate the radial profile of H i overdensity for MAMMOTH1-QSO, and find that MAMMOTH1-QSO resides in a volume with fairly weak H i absorption. This suggests that MAMMOTH1-QSO may have a proximity zone where quasar illuminates and photoionizes the surrounding H i gas and suppresses H i absorption, and that the ELAN is probably a photoionized cloud embedded in the cosmic web. The H i radial profile of MAMMOTH1-QSO is very similar to those of three neighboring type-I quasars at z = 2.3, which is compatible with the AGN unification model. We compare the distributions of the H i absorption and star-forming galaxies in our survey volume, and identify a spatial offset between density peaks of star-forming galaxies and H i gas. This segregation may suggest anisotropic UV background radiation created by star-forming galaxy density fluctuations.

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  • Large Population of ALMA Galaxies at z &gt; 6 with Very High [O iii] 88 μm to [C ii] 158 μm Flux Ratios: Evidence of Extremely High Ionization Parameter or PDR Deficit?

    Harikane, Y., Ouchi, M., Inoue, A.K., Matsuoka, Y., Tamura, Y., Bakx, T., Fujimoto, S., Moriwaki, K., Ono, Y., Nagao, T., Tadaki, K.-I., Kojima, T., Shibuya, T., Egami, E., Ferrara, A., Gallerani, S., Hashimoto, T., Kohno, K., Matsuda, Y., Matsuo, H., Pallottini, A., Sugahara, Y., Vallini, L.

    Astrophysical Journal   896 ( 2 ) 93 - 93  2020年  [査読有り]

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    115
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  • Balmer Break Galaxy Candidates at z ∼ 6: A Potential View on the Star Formation Activity at z ⪆ 14

    Mawatari, K., Inoue, A.K., Hashimoto, T., Silverman, J., Kajisawa, M., Yamanaka, S., Yamada, T., Davidzon, I., Capak, P., Lin, L., Hsieh, B.-C., Taniguchi, Y., Tanaka, M., Ono, Y., Harikane, Y., Sugahara, Y., Fujimoto, S., Nagao, T.

    Astrophysical Journal   889 ( 2 )  2020年  [査読有り]

     概要を見る

    We search for galaxies with a strong Balmer break (Balmer break galaxies; BBGs) at z 6 over a 0.41 deg2 effective area in the COSMOS field. Based on rich imaging data, including data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), three candidates are identified by their extremely red K [3.6] colors, as well as by nondetection in the X-ray, optical, far-infrared, and radio bands. The nondetection in the deep ALMA observations suggests that they are not dusty galaxies but BBGs at z 6, although contamination from active galactic nuclei at z 0 cannot be completely ruled out for the moment. Our spectral energy distribution analyses reveal that the BBG candidates at z 6 have stellar masses of x 101 M, dominated by old stellar populations with ages of > 700 Myr. Assuming that all three candidates are real BBGs at z 6, we estimate the stellar mass density to be 2.411 x 104 M. Mpc-3. This is consistent with an extrapolation from the lower-redshift measurements. The onset of star formation in the three BBG candidates is expected to be several hundred million yr before the observed epoch of z 6. We estimate the star formation rate density (SI-RD) contributed by progenitors of the BBGs to be 2.4-12 x 10-5 Mc, yr-1 Mpc3 at z > 14 (99.7% confidence range). Our result suggests a smooth evolution of the SFRD beyond z = 8.

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  • Fast outflows identified in early star-forming galaxies at z = 5-6

    Sugahara, Y., Ouchi, M., Harikane, Y., Bouché, N., Mitchell, P.D., Blaizot, J.

    Astrophysical Journal   886 ( 1 )  2019年  [査読有り]

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    34
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  • A Giant Green Pea Identified in the Spectroscopy of Spatially Extended [O iii] Sources

    Yuma, S., Ouchi, M., Fujimoto, S., Kojima, T., Sugahara, Y.

    Astrophysical Journal   882 ( 1 ) 17 - 17  2019年  [査読有り]

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    4
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  • The Hyper Suprime-Cam SSP survey: Overview and survey design

    Hiroaki Aihara, Nobuo Arimoto, Robert Armstrong, Stéphane Arnouts, Neta A. Bahcall, Steven Bickerton, James Bosch, Kevin Bundy, Peter L. Capak, James H. H. Chan, Masashi Chiba, Jean Coupon, Eiichi Egami, Motohiro Enoki, Francois Finet, Hiroki Fujimori, Seiji Fujimoto, Hisanori Furusawa, Junko Furusawa, Tomotsugu Goto, Andy Goulding, Johnny P. Greco, Jenny E. Greene, James E. Gunn, Takashi Hamana, Yuichi Harikane, Yasuhiro Hashimoto, Takashi Hattori, Masao Hayashi, Yusuke Hayashi, Krzysztof G. Hełminiak, Ryo Higuchi, Chiaki Hikage, Paul T. P. Ho, Bau-Ching Hsieh, Kuiyun Huang, Song Huang, Hiroyuki Ikeda, Masatoshi Imanishi, Akio K. Inoue, Kazushi Iwasawa, Ikuru Iwata, Anton T. Jaelani, Hung-Yu Jian, Yukiko Kamata, Hiroshi Karoji, Nobunari Kashikawa, Nobuhiko Katayama, Satoshi Kawanomoto, Issha Kayo, Jin Koda, Michitaro Koike, Takashi Kojima, Yutaka Komiyama, Akira Konno, Shintaro Koshida, Yusei Koyama, Haruka Kusakabe, Alexie Leauthaud, Chien-Hsiu Lee, Lihwai Lin, Yen-Ting Lin, Robert H. Lupton, Rachel Mandelbaum, Yoshiki Matsuoka, Elinor Medezinski, Sogo Mineo, Shoken Miyama, Hironao Miyatake, Satoshi Miyazaki, Rieko Momose, Anupreeta More, Surhud More, Yuki Moritani, Takashi J. M. Oriya, Tomoki Morokuma, Shiro Mukae, Ryoma Murata, Hitoshi Murayama, Tohru Nagao, Fumiaki Nakata, Mana Niida, Hiroko Niikura, Atsushi J. Nishizawa, Yoshiyuki Obuchi, Masamune Oguri, Yukie Oishi, Nobuhiro Okabe, Sakurako Okamoto, Yuki Okura, Yoshiaki Ono, Masato Onodera, Masafusa Onoue, Ken Osato, Masami Ouchi, Paul A. Price, Tae-Soo Pyo, Masao Sako, Marcin Sawicki, Takatoshi Shibuya, Kazuhiro Shimasaku, Atsushi Shimono, Masato Shirasaki, John D. Silverman, Melanie Simet, Joshua Speagle, David N. Spergel, Michael A. Strauss, Yuma Sugahara, Naoshi Sugiyama, Yasushi Suto, Sherry H. Suyu, Nao Suzuki, Philip J. Tait, Masahiro Takada, Tadafumi Takata, Naoyuki Tamura, Manobu M. Tanaka, Masaomi Tanaka, Masayuki Tanaka, Yoko Tanaka, Tsuyoshi Terai, Yuichi Terashima, Yoshiki Toba, Nozomu Tominaga, Jun Toshikawa, Edwin L. Turner, Tomohisa Uchida, Hisakazu Uchiyama, Keiichi Umetsu, Fumihiro Uraguchi, Yu Ji Urata, Tomonori Usuda, Yousuke Utsumi, Shiang-Yu Wang, Wei-Hao Wang, Kenneth C. Wong, Kiyoto Yabe, Yoshihiko Yamada, Hitomi Yamanoi, Naoki Yasuda, Sherry Yeh, Atsunori Yonehara, Suraphong Yuma

    Publications of the Astronomical Society of Japan   70 ( 1 )  2018年01月  [査読有り]

     概要を見る

    Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey.

    DOI

    Scopus

    710
    被引用数
    (Scopus)
  • First data release of the Hyper Suprime-Cam Subaru Strategic Program

    Hiroaki Aihara, Robert Armstrong, Steven Bickerton, James Bosch, Jean Coupon, Hisanori Furusawa, Yusuke Hayashi, Hiroyuki Ikeda, Yukiko Kamata, Hiroshi Karoji, Satoshi Kawanomoto, Michitaro Koike, Yutaka Komiyama, Dustin Lang, Robert H. Lupton, Sogo Mineo, Hironao Miyatake, Satoshi Miyazaki, Tomoki Morokuma, Yoshiyuki Obuchi, Yukie Oishi, Yuki Okura, Paul A. Price, Tadafumi Takata, Manobu M. Tanaka, Masayuki Tanaka, Yoko Tanaka, Tomohisa Uchida, Fumihiro Uraguchi, Yousuke Utsumi, Shiang-Yu Wang, Yoshihiko Yamada, Hitomi Yamanoi, Naoki Yasuda, Nobuo Arimoto, Masashi Chiba, Francois Finet, Hiroki Fujimori, Seiji Fujimoto, Junko Furusawa, Tomotsugu Goto, Andy Goulding, James E. Gunn, Yuichi Harikane, Takashi Hattori, Masao Hayashi, Krzysztof G. Helminiak, Ryo Higuchi, Chiaki Hikage, Paul T. P. Ho, Bau-Ching Hsieh, Kuiyun Huang, Song Huang, Masatoshi Imanishi, Ikuru Iwata, Anton T. Jaelani, Hung-Yu Jian, Nobunari Kashikawa, Nobuhiko Katayama, Takashi Kojima, Akira Konno, Shintaro Koshida, Haruka Kusakabe, Alexie Leauthaud, Chien-Hsiu Lee, Lihwai Lin, Yen-Ting Lin, Rachel Mandelbaum, Yoshiki Matsuoka, Elinor Medezinski, Shoken Miyama, Rieko Momose, Anupreeta More, Surhud More, Shiro Mukae, Ryoma Murata, Hitoshi Murayama, Tohru Nagao, Fumiaki Nakata, Mana Niida, Hiroko Niikura, Atsushi J. Nishizawa, Masamune Oguri, Nobuhiro Okabe, Yoshiaki Ono, Masato Onodera, Masafusa Onoue, Masami Ouchi, Tae-Soo Pyo, Takatoshi Shibuya, Kazuhiro Shimasaku, Melanie Simet, Joshua Speagle, David N. Spergel, Michael A. Strauss, Yuma Sugahara, Naoshi Sugiyama, Yasushi Suto, Nao Suzuki, Philip J. Tait, Masahiro Takada, Tsuyoshi Terai, Yoshiki Toba, Edwin L. Turner, Hisakazu Uchiyama, Keiichi Umetsu, Yuji Urata, Tomonori Usuda, Sherry Yeh, Suraphong Yuma

    Publications of the Astronomical Society of Japan   70 ( 1 )  2018年01月  [査読有り]

     概要を見る

    The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most important outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope, and it started in 2014 March. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7yr of observations (61.5 nights), and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i ∼ 26.4, ∼26.5, and ∼27.0mag, respectively (5a for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0".6 in the i band in the Wide layer. We show that we achieve 1%-2% point spread function (PSF) photometry (root mean square) both internally and externally (against Pan-STARRS1), and ∼10mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online.

    DOI

    Scopus

    418
    被引用数
    (Scopus)
  • Evolution of Galactic Outflows at z ∼ 0-2 Revealed with SDSS, DEEP2, and Keck Spectra

    Yuma Sugahara, Masami Ouchi, Lihwai Lin, Crystal L. Martin, Yoshiaki Ono, Yuichi Harikane, Takatoshi Shibuya, Renbin Yan

    Astrophysical Journal   850 ( 1 )  2017年11月  [査読有り]

     概要を見る

    We conduct a systematic study of galactic outflows in star-forming galaxies at z ∼ 0-2 based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck (Erb et al.). We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at z ∼ 0-2 and perform the multicomponent fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (vmax) and central (vout) outflow velocities and estimate the mass loading factors (η), a ratio of the mass outflow rate to the star formation rate (SFR). Investigating the redshift evolution of the outflow velocities measured with the absorption lines whose depths and ionization energies are similar (Na I D and Mg I at z ∼ 0-1
    Mg II and C II at z ∼ 1-2), we identify, for the first time, that the average value of vmax (vout) significantly increases by 0.05-0.3 dex from z ∼ 0 to 2 at a given SFR. Moreover, we find that the value of η increases from z ∼ 0 to 2 by η ∝ (1 + z)1.2±0.3 at a given halo circular velocity vcir, albeit with a potential systematics caused by model parameter choices. The redshift evolution of vmax (vout) and η is consistent with the galaxy-size evolution and the local velocity-SFR surface density relation and explained by high gas fractions in high-redshift massive galaxies, which is supported by recent radio observations. We obtain a scaling relation of η ∝ νcira for a = -0.2 ± 1.1 in our z ∼ 0 galaxies that agrees with the momentum-driven outflow model (a = -1) within the uncertainties.

    DOI

    Scopus

    35
    被引用数
    (Scopus)
  • Systematic Survey for [O II], [O III], and Hα Blobs at z = 0.1-1.5: The Implication for Evolution of Galactic-scale Outflow

    Suraphong Yuma, Masami Ouchi, Alyssa B. Drake, Seiji Fujimoto, Takashi Kojima, Yuma Sugahara

    Astrophysical Journal   841 ( 2 ) 93 - 93  2017年06月  [査読有り]

     概要を見る

    We conduct a systematic search for galaxies at z = 0.1 1.5-with [O II]λ3727, [O III]λ5007, or Hal6563 emission lines extended over at least 30 kpc by using deep narrowband and broadband imaging in the-Subaru-XMM Deep Survey field. These extended emission-line galaxies are dubbed [O II], [O III], or Ha blobs. Based on a new selection method that securely selects-extended emission-line galaxies, we find 77 blobs at z = 0.40 1.46-with the isophotal area of emission lines down to 1.2 × 10-18 erg s-1 cm-2 kpc-2. Four of them are spectroscopically confirmed to be [O III] blobs at z=0.83. We identify AGN activities in eight blobs with X-ray and radio data, and find that the fraction of AGN contribution increases with increasing isophotal area of the extended emission. With the Kolmogorov-Smirnov (KS) and Anderson-Darling tests, we confirm that the stellar-mass distributions of Ha and [O II] blobs are not drawn from those of the emitters at the &gt
    90% confidence level in that Ha and [O II] blobs are located at the massive end of the distributions, but cannot reject anull hypothesis of being the same distributions in terms of the specific star formation rates. It is suggested that galactic-scale outflows tend to be more prominent in more massive star-forming galaxies. Exploiting our sample homogeneously selected over the large area, we derive the number densities of blobs at each epoch. The number densities of blobs decrease drastically with redshifts at a rate that is larger than that of the decrease of cosmic star formation densities.

    DOI

    Scopus

    11
    被引用数
    (Scopus)

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共同研究・競争的資金等の研究課題

  • アウトフローの赤方偏移進化から読み解く銀河形成

    日本学術振興会  科学研究費助成事業

    研究期間:

    2018年04月
    -
    2020年03月
     

    菅原 悠馬

     概要を見る

    本研究課題をまとめた論文を Astrophysical Journal 誌に投稿し、出版した。この論文では、高赤方偏移 z=5-6 の銀河の可視分光データを解析することで、銀河から吹くアウトフローの最大速度が約 700 km/s と、低赤方偏移で同じ星質量をもつものより大きいことを示した。これまでこのような高赤方偏移におけるアウトフロー研究が困難であった理由として、吸収線解析に必要な銀河の赤方偏移を正確に決定することが難しかったことが挙げられる。本研究ではアルマ望遠鏡で観測された [CII]158um 輝線を利用することでこの困難を克服し、世界で初めて z=5-6 におけるアウトフローの最大速度を報告した。星形成銀河のアウトフローは、銀河の星形成活動を制御する主要なフィードバック機構の一つであると考えられており、本研究は銀河の形成初期におけるフィードバック活動の解明に寄与するものである。
    論文の改訂に際し、本研究の観測結果と最新の銀河形成シミュレーション研究の比較について議論を深めた。我々の観測結果は、z=0 から 6 という幅広い赤方偏移にわたって同様の星質量をもつ銀河のシミュレーションとよく合った。観測とシミュレーションにおけるアウトフローガスの温度の違いやサイズの違いについても検討した。本研究結果を国内・国際研究会や、国内外のセミナートークで発表した。
    さらに発展的課題として、アウトフローの空間的な広がりを制限するためにすばる望遠鏡の Hyper Suprime Cam による広域撮像データの統計的に処理した。また、銀河周囲から銀河へのガスの流れ(インフロー)を近傍の低金属量銀河の分光データから推定できないか検討した。

Misc

  • 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

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    菅原悠馬, 菅原悠馬, 徳岡剛史, 井上昭雄, 札本佳伸, 札本佳伸, 橋本拓也, 田村陽一

    日本天文学会年会講演予稿集   2022  2022年

    J-GLOBAL

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    徳岡剛史, 井上昭雄, 橋本拓也, ELLIS Richard S., LAPORTE Nicolas, 菅原悠馬, 松尾宏, 田村陽一, 札本佳伸, 森脇可奈, ROBERTS-BORSANI Guido, 清水一紘, 山中郷史, 吉田直紀, ZACKRRISON Erik, ZHENG Wei

    日本天文学会年会講演予稿集   2022  2022年

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  • ビッグ3Dragons:z=7.15での明るいLyman崩壊銀河における分子気体【JST・京大機械翻訳】

    橋本拓也, 井上昭雄, 菅原悠馬, 菅原悠馬, 札本佳伸, 札本佳伸, 藤本征史, 藤本征史, KIRSTEN Knudsen K., 松尾宏, 田村陽一, 山中郷史, 播金優一, 播金優一, 久野成夫, 小野宜昭, DRAGAN Salak

    日本天文学会年会講演予稿集   2022  2022年

    J-GLOBAL

  • 重力レンズ効果を考慮した回転円盤モデルフィッティングコードの開発

    徳岡剛史, 井上昭雄, 橋本拓也, 山中郷史, 菅原悠馬, 札本佳伸, 田村陽一, 松尾宏, 吉田直紀

    日本天文学会年会講演予稿集   2021  2021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

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    日本天文学会年会講演予稿集   2021  2021年

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