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

Research Project

Project/Area Number 19F19317
Research Category

Grant-in-Aid for JSPS Fellows

Allocation TypeSingle-year Grants
Section外国
Review Section Basic Section 16010:Astronomy-related
Research InstitutionThe University of Tokyo
Host Researcher 藤井 通子  東京大学, 大学院理学系研究科(理学部), 准教授 (90722330)
Foreign Research Fellow WANG LONG  東京大学, 理学(系)研究科(研究院), 外国人特別研究員
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
Project Status Granted (Fiscal Year 2021)
Budget Amount *help
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2021: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2020: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2019: ¥600,000 (Direct Cost: ¥600,000)
Keywordsstar cluster / N-body simulation / binary black hole / gravitational wave / numerical simulations / stellar dynamics / star formation / binary stars / stellar multiplicity
Outline of Research at the Start

Gravitational waves (GW) detection is a new channel of observing black hole (BH) and neutron star (NS), which are difficult to detect by using traditional telescopes. Thus, GW provides a unique way to study BHs/NSs. In this research, a series of large N-body simulations of star clusters, where GW progenitors can efficiently form, will be carried out to study correlations between star formation, stellar dynamics and properties of GW progenitors. Using the result, we make predictions of the characteristics of GW events, such as the mass of the progenitors, event rate and more detailed features.

Outline of Annual Research Achievements

The star-by-star N-body simulations of massive globular clusters (GCs) are important method to understand the long-term evolution of and predict the properties of gravitational wave (GW) events. The previous fastest N-body code, NBODY6++GPU, cannot handle dense massive GCs with many binaries. To overcome the bottleneck, we have developed the slow-down algorithmic regularization (SDAR) algorithm to efficiently handle the motions of multiple systems. Then, we developed a new N-body code, PeTar, which combines the particle-particle particle-tree method and the SDAR algorithm. Compared to NBODY6++GPU, PeTar can achieve 7-10 times faster computing speed for million-body simulations with many binaries. We have also implemented the code into ASURA-BRIDGE for simulating the formation of star clusters.
We have performed simulations of star clusters with different initial mass functions (IMFs) using our new code and found that the numbers of binary black holes merging with GW emission does not simply depends on the slope of the IMF. We also performed simulations of star clusters on Fugaku supercomputer. We are analyzing the data and will publish the results in the next fiscal year.

Current Status of Research Progress
Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The PeTar code is developed on time and shows excellent scaling on the XC50 supercomputer. Two papers related to it have been published. Now we have used it to carry out several studies related to GW events as the plan. One work on studying how the variation of IMF affects the GW events in GCs have finished and the paper is under review. The works on studying the impact of primordial binaries and the Galactic potential is ongoing. After implementing PeTar into the hydrodynamic code, ASURA-BRIDGE, we also studied how the dynamical formation and evolution of binaries affect the feedback to star formation.

Strategy for Future Research Activity

We will continue to carry out N-body models to investigate how the IMF, the primordial binaries and the Galactic potential affect the GW events in GCs. We will carry out the largest N-body model for GCs with 3 million stars by using the XC-50 and the Fugaku supercomputers. The models will be used to validate the approximate methods such as Monte-Carlo simulations and to predict the properties of GW events. In addition, we will carry out the simulation for nuclear star clusters with 10 million stars, to investigate whether the runaway collisions of stellar mass black holes can be the possible channel to form the seed of supermassive black hole. Moreover, we will continue to improve the performance and functions of the PeTar code.

Report

(2 results)
  • 2020 Annual Research Report
  • 2019 Annual Research Report

Research Products

(22 results)

All 2021 2020 2019 Other

All Int'l Joint Research (9 results) Journal Article (7 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 7 results,  Open Access: 1 results) Presentation (5 results) (of which Int'l Joint Research: 1 results) Remarks (1 results)

  • [Int'l Joint Research] The SPODYR Group/Charles University/GRANTECAN(チェコ)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] MPA/Astronomisches Rechen-Institut/Heidelberg University(ドイツ)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] NCAC(ポーランド)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] Columbia University/Princeton University(米国)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] Nicolaus Copernicus Astronomical Center(ポーランド)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] Lund University(スウェーデン)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] Leiden University(オランダ)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] Bonn Univesity/MPA, Garching(ドイツ)

    • Related Report
      2019 Annual Research Report
  • [Int'l Joint Research] Observatory of Astronomy in Padova(イタリア)

    • Related Report
      2019 Annual Research Report
  • [Journal Article] A slow-down time-transformed symplectic integrator for solving the few-body problem2020

    • Author(s)
      Wang Long、Nitadori Keigo、Makino Junichiro
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 493 Pages: 3398-3411

    • DOI

      10.1093/mnras/staa480

    • Related Report
      2020 Annual Research Report 2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] petar: a high-performance N-body code for modelling massive collisional stellar systems2020

    • Author(s)
      Wang Long、Iwasawa Masaki、Nitadori Keigo、Makino Junichiro
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 497 Pages: 536-555

    • DOI

      10.1093/mnras/staa1915

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Very high redshift quasars and the rapid emergence of super-massive black holes2020

    • Author(s)
      Kroupa Pavel、Subr Ladislav、Jerabkova Tereza、Wang Long
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 498 Pages: 5652-5683

    • DOI

      10.1093/mnras/staa2276

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Intermediate mass black hole formation in compact young massive star clusters2020

    • Author(s)
      Rizzuto Francesco Paolo、Naab Thorsten、Spurzem Rainer、Giersz Mirek、Ostriker J P、Stone N C、Wang Long、Berczik Peter、Rampp M
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 501 Pages: 5257-5273

    • DOI

      10.1093/mnras/staa3634

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] The survival of star clusters with black hole subsystems2020

    • Author(s)
      Wang Long
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 491 Pages: 2413-2423

    • DOI

      10.1093/mnras/stz3179

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Accelerated FDPS: Algorithms to use accelerators with FDPS2020

    • Author(s)
      Iwasawa Masaki、Namekata Daisuke、Nitadori Keigo、Nomura Kentaro、Wang Long、Tsubouchi Miyuki、Makino Junichiro
    • Journal Title

      Publications of the Astronomical Society of Japan

      Volume: 72 Pages: 13-13

    • DOI

      10.1093/pasj/psz133

    • NAID

      120006840182

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] The possible role of stellar mergers for the formation of multiple stellar populations in globular clusters2019

    • Author(s)
      Wang Long、Kroupa Pavel、Takahashi Koh、Jerabkova Tereza
    • Journal Title

      Monthly Notices of the Royal Astronomical Society

      Volume: 491 Pages: 440-454

    • DOI

      10.1093/mnras/stz3033

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] The 3 million-star simulations of globular clusters using Fugaku computer2021

    • Author(s)
      Long Wang
    • Organizer
      ASJ 2021 Spring Annual Meeting
    • Related Report
      2020 Annual Research Report
  • [Presentation] The impact of IMFs on the dynamical channels of gravitational wave sources,2021

    • Author(s)
      Long Wang
    • Organizer
      GW Genesis: Group A Winter Camp 2021
    • Related Report
      2020 Annual Research Report
  • [Presentation] The connection between dynamical evolution of star clusters, IMFs and BH mergers2020

    • Author(s)
      Long Wang
    • Organizer
      GW Genesis:First Stars & First Galaxies 2020
    • Related Report
      2020 Annual Research Report
  • [Presentation] PeTar a high-performance N-body code for modelling massive collisional stellar systems2020

    • Author(s)
      Long Wang
    • Organizer
      IAU CB1 CHALLENGES AND INNOVATIONS IN COMPUTATIONAL ASTROPHYSICS - II
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] The connection between stellar dynamics and BH mergers2020

    • Author(s)
      Long Wang
    • Organizer
      Gravitational Wave Physics and Astronomy: Genesis
    • Related Report
      2019 Annual Research Report
  • [Remarks] GitHub

    • URL

      https://github.com/lwang-astro

    • Related Report
      2020 Annual Research Report

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Published: 2019-11-29   Modified: 2021-12-27  

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