Theoretical Study on Formation of Supermassive Black Holes

• Project/Area Number: 17H01102
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Astronomy
• Research Institution: Tohoku University
• Principal Investigator: 大向 一行 東北大学, 理学研究科, 教授 (70390622)
• Co-Investigator(Kenkyū-buntansha): 細川 隆史 京都大学, 理学研究科, 准教授 (30413967) ; 大須賀 健 筑波大学, 計算科学研究センター, 教授 (90386508)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Project Status: Granted (Fiscal Year 2021)
• Budget Amount: ¥43,940,000 (Direct Cost: ¥33,800,000、Indirect Cost: ¥10,140,000); Fiscal Year 2021: ¥8,840,000 (Direct Cost: ¥6,800,000、Indirect Cost: ¥2,040,000); Fiscal Year 2020: ¥9,360,000 (Direct Cost: ¥7,200,000、Indirect Cost: ¥2,160,000); Fiscal Year 2019: ¥8,840,000 (Direct Cost: ¥6,800,000、Indirect Cost: ¥2,040,000); Fiscal Year 2018: ¥8,840,000 (Direct Cost: ¥6,800,000、Indirect Cost: ¥2,040,000); Fiscal Year 2017: ¥8,060,000 (Direct Cost: ¥6,200,000、Indirect Cost: ¥1,860,000)
• Keywords: 巨大ブラックホール / 宇宙初期天体 / 銀河形成 / 星形成 / 活動銀河核

Outline of Annual Research Achievements

我々の銀河系をはじめ、ある程度大きな銀河の中心部には太陽質量の100万倍から10億倍程度の巨大ブラックホールが存在しているが、その起源は謎に包まれている。宇宙誕生後、10億年に満たない時期においてもこのような巨大ブラックホールがいくつか発見されていることから、巨大ブラックホールの起源は宇宙初期にあり、種となったブラックホールからの成長時間も短いことから、最初の種質量も通常の星よりもずっと大質量なものが望ましいと考えられる。
そのような大質量の種ブラックホールの起源として、本計画では巨大星形成とその直接崩壊によるブラックホール形成を考えている。これまで始原ガスの特殊な環境では巨大星が形成されえることは知られていたが、そのような環境は極めて稀であり、銀河中心に普遍的に存在する巨大ブラックホールの種としては数が少なすぎた。そこで今回、紫外線の照射のものでの微量の重元素を含むようなガスからの星形成過程を3次元数値流体シミュレーションにより解析したところ、ガスの分裂により星団が形成され、構成する星たちは競争的に周囲のガスを獲得して成長するものの、最も大きな星はその中心に存在して、ほぼ独占的に他より多くのガスを降着して成長し、10万太陽質量以上の巨大な星となり重力崩壊することが分かった（「超競争的降着」）。このように強い紫外線がある環境は、通常、微量の重元素を持っているとかんがえられ、始原ガスの場合に比べて多くの種ブラックホールを生成できると予想される。

Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

当初の研究計画と比べ大きな送れなく研究が遂行できているうえに、当初計画の始原ガスの直接崩壊による種ブラックホール形成過程に加えて、重元素をもつ低金属度雲中での超競争的降着による種ブラックホール形成チャネルが新たに見いだされた。

Strategy for Future Research Activity

これまでほぼ当初の研究計画以上の研究を遂行出来ている。計画最終年度となる次年度もこのペースを継続して、当初計画のうちやり残した部分の完成に向けて、分担者とも協力して研究を推進する予定である。

Research Products

• [Int'l Joint Research] Sapienza University of Rome(イタリア)
• [Int'l Joint Research] KIAA, Peking University(中国)
• [Int'l Joint Research] Columbia University(米国)
• [Int'l Joint Research] Sapienza University of Rome/Scuola Normale Superiore, Pisa(イタリア)
• [Int'l Joint Research] National Astronomical Observatories(中国)
• [Journal Article] The Birth of a Massive First-star Binary (2020)
  • Author(s): Sugimura Kazuyuki、Matsumoto Tomoaki、Hosokawa Takashi、Hirano Shingo、Omukai Kazuyuki
  • Journal Title: ApJL Volume: 892
  • DOI: 10.3847/2041-8213/ab7d37
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Supermassive star formation via super competitive accretion in slightly metal-enriched clouds (2020)
  • Author(s): Chon Sunmyon、Omukai Kazuyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 494 Pages: 2851-2860
  • DOI: 10.1093/mnras/staa863
  • Peer Reviewed
• [Journal Article] Gravitational stability and fragmentation condition for discs around accreting supermassive stars (2019)
  • Author(s): Matsukoba Ryoki , Takahashi Sanemichi Z , Sugimura Kazuyuki , Omukai Kazuyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 484 Pages: 26052619-26052619
  • DOI: 10.1093/mnras/sty3522
  • Peer Reviewed
• [Journal Article] Ionization degree and magnetic diffusivity in the primordial star-forming clouds (2019)
  • Author(s): Nakauchi Daisuke、Omukai Kazuyuki、Susa Hajime
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 488 Pages: 1846-1862
  • DOI: 10.1093/mnras/stz1799
  • Peer Reviewed
• [Journal Article] Spectral energy distribution of the first galaxies: contribution from pre-main-sequence stars (2019)
  • Author(s): Mitani Hiroto、Yoshida Naoki、Omukai Kazuyuki、Hosokawa Takashi
  • Journal Title: MNRAS Volume: 488
  • DOI: 10.1093/mnrasl/slz100
  • Peer Reviewed
• [Journal Article] Magnetohydrodynamic Simulations of a Plunging Black Hole into a Molecular Cloud (2019)
  • Author(s): Nomura Mariko、Oka Tomoharu、Yamada Masaya、Takekawa Shunya、Ohsuga Ken、Takahashi Hiroyuki R.、Asahina Yuta
  • Journal Title: The Astrophysical Journal Volume: 859 Pages: 29-29
  • DOI: 10.3847/1538-4357/aabe32
  • Peer Reviewed
• [Journal Article] Super-Eddington accretion of dusty gas onto seed black holes: metallicity-dependent efficiency of mass growth (2019)
  • Author(s): Toyouchi Daisuke , Hosokawa Takashi , Sugimura Kazuyuki , Nakatani Riouhei , Kuiper Rolf
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: - Pages: 2031-2043
  • DOI: 10.1093/mnras/sty3012
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Condition for dust evacuation from the first galaxies (2018)
  • Author(s): Fukushima Hajime , Yajima Hidenobu , Omukai Kazuyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 477 Pages: 10711085-10711085
  • DOI: 10.1093/mnras/sty799
  • Peer Reviewed
• [Journal Article] Stunted accretion growth of black holes by combined effect of the flow angular momentum and radiation feedback (2018)
  • Author(s): Sugimura Kazuyuki , Hosokawa Takashi , Yajima Hidenobu , Inayoshi Kohei , Omukai Kazuyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 478 Pages: 39613975-39613975
  • DOI: 10.1093/mnras/sty1298
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Condition for low-mass star formation in shock-compressed metal-poor clouds (2018)
  • Author(s): Nakauchi Daisuke , Omukai Kazuyuki , Schneider Raffaella
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 480 Pages: 10431056-10431056
  • DOI: 10.1093/mnras/sty1911
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Rapid growth of black holes accompanied with hot or warm outflows exposed to anisotropic super-Eddington radiation (2018)
  • Author(s): Takeo Eishun、Inayoshi Kohei、Ohsuga Ken、Takahashi Hiroyuki R、Mineshige Shin
  • Journal Title: Mon. Notices. Roy. Astron. Soc. Volume: 476 Pages: 673-673
  • DOI: 10.1093/mnras/sty264
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Systematic two-dimensional radiation-hydrodynamic simulations of super-Eddington accretion flow and outflow: Comparison with the slim disk model (2018)
  • Author(s): Kitaki, Takaaki; Mineshige, Shin; Ohsuga, Ken; Kawashima, Tomohisa
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 70 Pages: 108-108
  • DOI: 10.1093/pasj/psy110
  • NAID: 120007133430
  • Peer Reviewed
• [Journal Article] Radiation hydrodynamics simulations of the formation of direct-collapse supermassive stellar systems (2018)
  • Author(s): S. Chon, T. Hosokawa, N. Yoshida
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 475 Pages: 4104-4121
  • DOI: 10.1093/mnras/sty086
  • Peer Reviewed
• [Journal Article] Triggering the Formation of Direct Collapse Black Holes by Their Congeners (2017)
  • Author(s): Yue, Bin; Ferrara, Andrea; Pacucci, Fabio; Omukai, Kazuyuki
  • Journal Title: The Astrophysical Journal Volume: 838 Pages: 111-111
  • DOI: 10.3847/1538-4357/aa6627
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Rapid Black Hole Growth under Anisotropic Radiation Feedback (2017)
  • Author(s): Sugimura, Kazuyuki; Hosokawa, Takashi; Yajima, Hidenobu; Omukai, Kazuyuki
  • Journal Title: MNRAS Volume: 未定 Pages: 62-79
  • DOI: 10.1093/mnras/stx769
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Fates of the dense cores formed by fragmentation of filaments: do they fragment again or not? (2017)
  • Author(s): Sugimura Kazuyuki、Mizuno Yurina、Matsumoto Tomoaki、Omukai Kazuyuki
  • Journal Title: MNRAS Volume: 469 Pages: 4022-4033
  • DOI: 10.1093/mnras/stx1129
  • Peer Reviewed
• [Journal Article] Primordial protostars accreting beyond the ΩΓ-limit: radiation effect around the star-disc boundary (2017)
  • Author(s): Takahashi Sanemichi Z. , Omukai Kazuyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 472 Pages: 532-541
  • DOI: 10.1093/mnras/stx1988
  • Peer Reviewed
• [Journal Article] Upper stellar mass limit by radiative feedback at low-metallicities: metallicity and accretion rate dependence (2017)
  • Author(s): Fukushima Hajime、Omukai Kazuyuki、Hosokawa Takashi
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 473 Pages: 4754-4772
  • DOI: 10.1093/mnras/stx2620
  • Peer Reviewed
• [Presentation] Origin of Supermassive Black Holes: Theoretical Perspective (2019)
  • Author(s): Kazuyuki Omukai
  • Organizer: Asia Pacific Physics Conference APPC14 Astrophysics, Cosmology, and Gravitation Sessions
  • Int'l Joint Research / Invited
• [Presentation] Binary Star Formation at Low Metallicities (2019)
  • Author(s): Kazuyuki Omukai
  • Organizer: YKIS2019 "Black Holes and Neutron Stars with Gravitational Waves"
  • Int'l Joint Research
• [Presentation] 宇宙初期の星形成におけるダストの役割 (2019)
  • Author(s): 大向一行
  • Organizer: 銀河の化学進化とダスト形成
  • Invited
• [Presentation] From First Stars to First Black Holes (2018)
  • Author(s): Kazuyuki Omukai
  • Organizer: The early growth of supermassive black holes
  • Int'l Joint Research / Invited
• [Presentation] Feedback from accreting seed black holes and progenitor stars (2018)
  • Author(s): Takashi Hosokawa
  • Organizer: The early growth of supermassive black holes
  • Int'l Joint Research / Invited
• [Presentation] Status Report of A03 in FY2018: Quest for BH binary (2018)
  • Author(s): Kazuyuki Omukai
  • Organizer: The Second annual symposium of the innovative area "Gravitational Wave Physics and Astronomy: Genesis"
  • Int'l Joint Research / Invited
• [Presentation] Radiation-MHD simulations of accretion flows and outflows around black holes and neutron stars (2018)
  • Author(s): Ken Ohsuga
  • Organizer: Max-Planck/Princeton Center for Plasma Physics Workshop
• [Presentation] Super-Eddington flows and spectra (2018)
  • Author(s): Ken Ohsuga
  • Organizer: ULTRA-LUMINOUS X-RAY PULSARS
• [Presentation] Understanding primordial star formation: Francesco's contribution (2017)
  • Author(s): Kazuyuki Omukai
  • Organizer: Francesco's Legacy: Star Formation in Space and Time
  • Int'l Joint Research / Invited
• [Book] ブラックホールをのぞいてみたら (2017)
  • Author(s): 大須賀 健
  • Total Pages: 256
  • Publisher: ＫＡＤＯＫＡＷＡ
  • ISBN: 9784041061848
• [Book] マルいアタマをもっとマルく！日能研クエスト 宇宙のふしぎ最前線！ 謎だらけの宇宙にいどむ (2017)
  • Author(s): 大須賀 健、日能研
  • Total Pages: 200
  • Publisher: 講談社
  • ISBN: 9784062206723