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2021 Fiscal Year Annual Research Report

Evolution of star clusters: from star fromation to gravitational wave emission

Research Project

Project/Area Number 19F19317
Research InstitutionThe University of Tokyo

Principal Investigator

藤井 通子  東京大学, 大学院理学系研究科(理学部), 准教授 (90722330)

Co-Investigator(Kenkyū-buntansha) WANG LONG  東京大学, 理学(系)研究科(研究院), 外国人特別研究員
Project Period (FY) 2019-11-08 – 2022-03-31
Keywords星団 / ブラックホール連星 / N体シミュレーション
Outline of Annual Research Achievements

We have developed a new N-body code, PeTar. Comparing the previous fastest code, the new code has several significant advantages: 1, For more than 100,000 stars, the performance of the code is much faster; 2. Using the slow-down algorithmic regularization method, it can handle 100 % binary fraction; 3. It has a well-designed user interface with rich data analysis tools; 4. It is modularized, and thus, including new functions from other codes.
By including updated stellar evolution code, BSE, we have investigated how the top-heavy IMF affects the event rate of GWs, we found that GCs with a top-heavy IMF is not efficient to produce GW mergers due to a low density after a strong expansion because of massive stellar wind mass loss. We also found the mass ratio distribution of BBHs is also different from that of GCs with the canonical IMF.
We have also carried out the first N-body models of intermediate massive star clusters with up to 100% binary fractions. We found that only massive primordial binaries can affect the long-term evolution of star clusters, but the effect is weak. This suggests that we can ignore low-mass binaries in the numerical modelling of GCs if we only care about the GW events.
By including PeTar in the hydrodynamical code, ASURA+BRIDGE, we studied how the OB binary affect the star formation of Orion nebular star clusters (ONC). We found the ejection of OB stars significantly affect the HII region in star-forming region, and thus, the binary dynamics affect the formation of multiple stellar population in ONC.

Research Progress Status

令和3年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和3年度が最終年度であるため、記入しない。

  • Research Products

    (10 results)

All 2021 Other

All Int'l Joint Research (2 results) Journal Article (3 results) (of which Peer Reviewed: 3 results) Presentation (4 results) (of which Int'l Joint Research: 2 results) Remarks (1 results)

  • [Int'l Joint Research] University of Padova(イタリア)

    • Country Name
      ITALY
    • Counterpart Institution
      University of Padova
  • [Int'l Joint Research] Nicolaus Copernicus Astronomical Center(ポーランド)

    • Country Name
      POLAND
    • Counterpart Institution
      Nicolaus Copernicus Astronomical Center
  • [Journal Article] SIRIUS project. III. Star-by-star simulations of star cluster formation using a direct N-body integrator with stellar feedback2021

    • Author(s)
      Fujii Michiko S、Saitoh Takayuki R、Hirai Yutaka、Wang Long
    • Journal Title

      Publications of the Astronomical Society of Japan

      Volume: 73 Pages: 1074~1099

    • DOI

      10.1093/pasj/psab061

    • Peer Reviewed
  • [Journal Article] SIRIUS project. II. A new tree-direct hybrid code for smoothed particle hydrodynamics/N-body simulations of star clusters2021

    • Author(s)
      Fujii Michiko S、Saitoh Takayuki R、Wang Long、Hirai Yutaka
    • Journal Title

      Publications of the Astronomical Society of Japan

      Volume: 73 Pages: 1057~1073

    • DOI

      10.1093/pasj/psab037

    • Peer Reviewed
  • [Journal Article] Impact of initial mass functions on the dynamical channel of gravitational wave sources2021

    • Author(s)
      Wang Long、Fujii Michiko S、Tanikawa Ataru
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 504 Pages: 5778~5787

    • DOI

      10.1093/mnras/stab1157

    • Peer Reviewed
  • [Presentation] The impact of IMFs on the dynamical channels of gravitational wave sources2021

    • Author(s)
      Long Wang
    • Organizer
      CHALLENGES AND INNOVATIONS IN COMPUTATIONAL ASTROPHYSICS III
    • Int'l Joint Research
  • [Presentation] The implementation of PeTar in AMUSE2021

    • Author(s)
      Long Wang
    • Organizer
      MODEST-21a: AMUSE
    • Int'l Joint Research
  • [Presentation] Impact of initial mass functions on the dynamical channel of gravitational wave sources2021

    • Author(s)
      Long Wang
    • Organizer
      GW Genesis: new science A03 workshop
  • [Presentation] Impact of initial mass functions on the dynamical channel of gravitational wave sources2021

    • Author(s)
      Long Wang
    • Organizer
      ASJ 2021 Autumn Annual Meeting
  • [Remarks] SIRIUS Project

    • URL

      https://sites.google.com/g.ecc.u-tokyo.ac.jp/sirius-project/

URL: 

Published: 2022-12-28  

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