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-Body代码，Petar。与以前最快的代码相比，新代码具有几个显著的优势：1、对于超过10万颗恒星，代码的执行速度要快得多；2、使用减速算法正则化方法，可以处理100%的二进制分数；3、设计良好的用户界面，具有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。通过包括更新的恒星演化代码BSE，我们研究了顶重IMF对GWS事故率的影响，我们发现，具有顶重IMF的GCs由于大量恒星风质量损失而在强膨胀后密度较低，不能有效地产生GW合并。我们还发现BBH的质量比分布也不同于具有正则IMF的GC的质量比分布。我们还首次实现了中等质量星团的N体模型，其二元分数最高可达100%。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，但影响很小。这表明，如果我们只关心GW事件，我们就可以在GCS的数值模拟中忽略低质量双星。通过将Petar包含在流体力学程序Asura+Bridge中，我们研究了OB双星对猎户座星云星团(ONC)恒星形成的影响。我们发现OB星的抛射显著地影响了恒星形成区的HII区，因此，双星动力学影响了ONC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