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Numerical simulations of the formation of the first galaxies

Research Project

Project/Area Number 16J03421
Research Category

Grant-in-Aid for JSPS Fellows

Allocation TypeSingle-year Grants
Section国内
Research Field Astronomy
Research InstitutionKonan University

Principal Investigator

千秋 元  甲南大学, 自然科学研究科, 特別研究員(PD)

Project Period (FY) 2016-04-22 – 2019-03-31
Project Status Completed (Fiscal Year 2018)
Budget Amount *help
¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2016: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Keywords星形成 / 金属欠乏星 / 初代星 / 初代銀河 / 銀河形成 / 低質量星 / 星間ダスト
Outline of Annual Research Achievements

本研究の最終目標は、初代銀河における星の質量分布と金属量分布を知ることである。星質量分布と金属量分布は相互に影響を及ぼすことが知られているが、それぞれ別々に議論されてきた(e.g. Omukai 2000; Ritter et al. 2016)。そこで本研究ではその相互作用の第一歩である、初代星の超新星爆発から金属欠乏星形成までの一連のプロセスを数値シミュレーションで追った。
本研究では、N体/Adaptive Mesh Refinement (AMR)コードenzoを用いて宇宙論的シミュレーションを行った。300共動kpcの計算領域内で赤方偏移12.1において1e6 Msunのミニハローが形成された。ハロー中心に13 Msunの初代星粒子を置き、これを光源として電離光子輻射による電離領域形成と超新星衝撃波の伝播を追った。超新星衝撃波は電離波面外部の高密度領域を通過するため、放射冷却によるエネルギー損失によって衝撃波がハローに落下し、再収縮を起こした。再収縮領域の中心から~1 pcの範囲内で金属量はほぼ一定の値2.6e-4 Zsunとなった。
つぎに私は再収縮領域の重力収縮過程を追った。本研究では、ダストが気相中の金属分子の降着により成長するダスト成長を初めて取り入れた。密度10^11 /ccにおいてSiO分子のシリケイトダスト(Mg2SiO4, MgSiO3)への降着により、ダスト成長が起こる。密度10^14/ccにおいて連続光に対してガスの光学的厚みが大きくなり、ダスト冷却率が小さくなると、原始星コアが形成される。その質量は0.06 Msunであり、小質量星形成が示唆された。この研究から、一回の超新星爆発でミニハローの自己汚染により、現在観測されている長寿命つまり小質量(<0.8 Msun)の金属欠乏星が形成されることが示唆される。

Research Progress Status

平成30年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

平成30年度が最終年度であるため、記入しない。

Report

(3 results)
  • 2018 Annual Research Report
  • 2017 Annual Research Report
  • 2016 Annual Research Report
  • Research Products

    (24 results)

All 2018 2017 2016

All Journal Article (5 results) (of which Int'l Joint Research: 1 results,  Peer Reviewed: 5 results,  Open Access: 5 results,  Acknowledgement Compliant: 1 results) Presentation (19 results) (of which Int'l Joint Research: 10 results,  Invited: 3 results)

  • [Journal Article] Seeding the second star: enrichment from population III, dust evolution, and cloud collapse2018

    • Author(s)
      Chiaki Gen、Wise John H
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 482 Issue: 3 Pages: 3933-3949

    • DOI

      10.1093/mnras/sty2984

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Metal-poor star formation triggered by the feedback effects from Pop III stars2018

    • Author(s)
      Chiaki Gen、Susa Hajime、Hirano Shingo
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 475 Issue: 4 Pages: 4378-4395

    • DOI

      10.1093/mnras/sty040

    • Related Report
      2017 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Blocking Metal Accretion onto Population III Stars by Stellar Wind2017

    • Author(s)
      Tanaka Shuta J.、Chiaki Gen、Tominaga Nozomu、Susa Hajime
    • Journal Title

      The Astrophysical Journal

      Volume: 844 Issue: 2 Pages: 137-137

    • DOI

      10.3847/1538-4357/aa7e2c

    • Related Report
      2017 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Classification of extremely metal-poor stars: absent region in A(C)-[Fe/H] plane and the role of dust cooling2017

    • Author(s)
      Chiaki Gen、Tominaga Nozomu、Nozawa Takaya
    • Journal Title

      Monthly Notices of the Royal Astronomical Society: Letters

      Volume: 472 Issue: 1 Pages: L115-L119

    • DOI

      10.1093/mnrasl/slx163

    • Related Report
      2017 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Gravitational collapse and the thermal evolution of low-metallicity gas clouds in the early Universe2016

    • Author(s)
      Gen Chiaki, Naoki Yoshida, Shingo Hirano
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 463 Issue: 3 Pages: 2781-2798

    • DOI

      10.1093/mnras/stw2120

    • Related Report
      2016 Annual Research Report
    • Peer Reviewed / Open Access / Acknowledgement Compliant
  • [Presentation] The first matter cycle in the Universe: from Pop III stars to Pop II stars2018

    • Author(s)
      Chiaki Gen、Susa Hajime、 Hirano Shingo
    • Organizer
      EWASS 2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Metal-poor star formation with feedback effects of photoionization and supernova of the first star2018

    • Author(s)
      Chiaki Gen
    • Organizer
      Enzo Days 2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] First Matter Cycle from Population III to Population II Stars2018

    • Author(s)
      Chiaki Gen
    • Organizer
      JINA-CEE Frontiers in Nuclear Astrophysics 2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Constraint on properties of dust grains created by Population III supernovae2018

    • Author(s)
      Chiaki Gen
    • Organizer
      CPHDUST2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 初代星超新星のフィードバックを考慮した金属欠乏星形成2018

    • Author(s)
      千秋元
    • Organizer
      初代星・初代銀河研究会2018
    • Related Report
      2018 Annual Research Report
  • [Presentation] The first matter cycle in the Universe: from Population III to extremely metal-poor stars2018

    • Author(s)
      Chiaki Gen
    • Organizer
      Stellar Archaeology as a Time Machine to the First Stars
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] 初代星超新星による金属汚染と金属欠乏星形成2018

    • Author(s)
      千秋 元
    • Organizer
      初代星・初代銀河研究会2017
    • Related Report
      2017 Annual Research Report
    • Invited
  • [Presentation] 初代星によるフィードバックを考慮した金属欠乏星形成環境2017

    • Author(s)
      千秋 元、須佐 元
    • Organizer
      天文学会 春季年会
    • Place of Presentation
      九州大学
    • Year and Date
      2017-03-15
    • Related Report
      2016 Annual Research Report
  • [Presentation] Formation environment of Pop II stars affected by the feedbacks from Pop III stars2017

    • Author(s)
      Chiaki Gen
    • Organizer
      Francesco’s Legacy: Star Formation in Space and Time
    • Related Report
      2017 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Formation environment of Pop II stars affected by the feedback from various Pop III stars2017

    • Author(s)
      Ghiaki Gen
    • Organizer
      EWASS 2017
    • Related Report
      2017 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Formation Condition and Classification of Extremely Metal-Poor Stars: Absent Region in the A(C)-[Fe/H] Plane2017

    • Author(s)
      Chiaki Gen
    • Organizer
      A Celebration of CEMP and a Gala of GALAH
    • Related Report
      2017 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 初代星超新星による重元素拡散過程2017

    • Author(s)
      千秋 元
    • Organizer
      理論懇シンポジウム 2017
    • Related Report
      2017 Annual Research Report
  • [Presentation] 金属欠乏星はどのように形成されたか2016

    • Author(s)
      千秋 元
    • Organizer
      第29回 理論懇シンポジウム
    • Place of Presentation
      東北大学
    • Year and Date
      2016-12-20
    • Related Report
      2016 Annual Research Report
  • [Presentation] Dust properties in the early Universe traced back from the elemental abundance of extremely metal-poor stars2016

    • Author(s)
      千秋 元
    • Organizer
      第33回 Grain Formation Workshop
    • Place of Presentation
      志賀島
    • Year and Date
      2016-12-12
    • Related Report
      2016 Annual Research Report
  • [Presentation] The origin of extremely metal-poor stars2016

    • Author(s)
      千秋 元
    • Organizer
      Workshop on Theoretical Astronomy 2016
    • Place of Presentation
      富山大学
    • Year and Date
      2016-11-14
    • Related Report
      2016 Annual Research Report
    • Invited
  • [Presentation] 金属欠乏星の起源2016

    • Author(s)
      千秋 元
    • Organizer
      初代星・初代銀河研究会 2016
    • Place of Presentation
      金沢市
    • Year and Date
      2016-10-25
    • Related Report
      2016 Annual Research Report
  • [Presentation] 金属欠乏星は形成時から金属を持っていたか2016

    • Author(s)
      千秋 元、須佐 元
    • Organizer
      天文学会 秋季年会
    • Place of Presentation
      愛媛大学
    • Year and Date
      2016-09-14
    • Related Report
      2016 Annual Research Report
  • [Presentation] Numerical studies of star formation in metal-poor clouds2016

    • Author(s)
      Gen Chiaki
    • Organizer
      RESCEU Summer School 2016
    • Place of Presentation
      高山市
    • Year and Date
      2016-08-24
    • Related Report
      2016 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Chemo-thermal Evolution of Collapsing Gas Cloud and the Formation of Metal-poor Stars2016

    • Author(s)
      Gen Chiaki, Naoki Yoshida, Shingo Hirano
    • Organizer
      First Stars V
    • Place of Presentation
      Heidelberg
    • Year and Date
      2016-08-01
    • Related Report
      2016 Annual Research Report
    • Int'l Joint Research

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Published: 2016-05-17   Modified: 2024-03-26  

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