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

星团的演化：从恒星形成到引力波发射

• 批准号: 19F19317
• 负责人: 藤井 通子
• 金额: $ 1.22万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for JSPS Fellows
• 财政年份: 2019
• 资助国家: 日本
• 起止时间: 2019-11-08 至 2022-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-19F19317/
• 关键词: 星団; ブラックホール連星; N体シミュレーション; star cluster; N-body simulation; binary black hole; gravitational wave; numerical simulations; stellar dynamics; star formation; binary stars; stellar multiplicity

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.

我们开发了一个新的n体代码，PeTar。与以往最快的代码相比，新代码有几个显著的优势：1、对于10万颗以上的星星，代码的性能要快得多；2. 采用慢速算法正则化方法，可以处理100%的二进制分数；3. 它有一个精心设计的用户界面和丰富的数据分析工具；4. 它是模块化的，因此包含了来自其他代码的新功能。通过加入最新的恒星演化代码BSE，我们研究了头重头重的IMF如何影响GW的事件率，我们发现，由于大量的恒星风质量损失，头重头重IMF的GCs在强膨胀后密度低，因此不能有效地产生GW合并。我们还发现BBHs的质量比分布也不同于典型IMF的GCs。我们还进行了第一个具有高达100%二元分数的中间大质量星团的n体模型。我们发现，只有大质量的原始双星才能影响星团的长期演化，但这种影响很弱。这表明，如果我们只关心GW事件，我们可以在GCs的数值模拟中忽略低质量双星。通过在流体动力学代码ASURA+BRIDGE中加入PeTar，我们研究了OB双星如何影响猎户座星云星团（ONC）的恒星形成。我们发现OB恒星的抛射对恒星形成区的HII区有显著影响，因此双星动力学影响ONC中多恒星群的形成。

项目成果

Accelerated FDPS: Algorithms to use accelerators with FDPS

加速 FDPS：使用 FDPS 加速器的算法

• DOI: 10.1093/pasj/psz133
• 发表时间: 2020
• 期刊: Publications of the Astronomical Society of Japan
• 影响因子: 2.3
• 作者: Iwasawa Masaki;Namekata Daisuke;Nitadori Keigo;Nomura Kentaro;Wang Long;Tsubouchi Miyuki;Makino Junichiro
• 通讯作者: Makino Junichiro

Leiden University(オランダ)

莱顿大学（荷兰）

Observatory of Astronomy in Padova(イタリア)

帕多瓦天文台（意大利）

SIRIUS Project

天狼星计划

The 3 million-star simulations of globular clusters using Fugaku computer

使用富岳计算机对球状星团的 300 万颗恒星进行模拟

• 发表时间: 2021
• 作者: Koyanagi I;Sonomura K;Naoi T;Ohnishi T;Kaneko N;Sawamoto K;Sato TA;Sakaguchi M;Long Wang
• 通讯作者: Long Wang