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.

我们开发了一种新的 N 体代码 PeTar。相比之前最快的代码，新代码有几个显着的优势： 1、对于超过10万颗星，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. 拥有精心设计的用户界面，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。通过包含更新的恒星演化代码BSE，我们研究了头重脚轻的IMF如何影响GW的事件率，我们发现头重脚轻的GC由于大量恒星风质量损失导致强烈膨胀后密度较低，IMF 无法有效地产生 GW 合并。我们还发现BBH的质量比分布也与具有规范IMF的GC不同。我们还建立了第一个具有高达100%二元分数的中等大质量星团的N体模型。我们发现只有大质量的原初双星才能影响星团的长期演化，但效果较弱。这表明，如果我们只关心GW事件，我们可以在GC数值模拟中忽略低质量双星。通过将PeTar包含在流体动力学代码ASURA+BRIDGE中，我们研究了OB双星如何影响猎户座星云的恒星形成星团（ONC）。我们发现OB星的抛射显着影响恒星形成区的HII区，因此，双星动力学影响ONC中多星族的形成。

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

Nicolaus Copernicus Astronomical Center(ポーランド)

尼古拉斯·哥白尼天文中心（波兰）