The impact of primordial binary on the dynamical evolution of intermediate massive star clusters
The impact of primordial binary on the dynamical evolution of intermediate massive star clusters
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原初双星对中等质量星团动力学演化的影响
DOI：
10.1093/mnras/stab3255
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发表时间：
2021
影响因子：
4.8
通讯作者：
Fujii Michiko S
中科院分区：
文献类型：
--
作者：
Wang Long;Tanikawa Ataru;Fujii Michiko S
观测发现，星星团包含了大部分的双星。紧双星是影响星星团长期动力学演化的重要热源。然而，由于N体工具的局限性，以往的球状星团直接N体模拟理论没有研究大部分原始双星对它们长期演化的影响。在这项工作中，我们使用高性能的N体程序petar，对原始双星分数从0到1变化的中等质量GC（N= 100 000）进行逐星星模型。我们发现，当恒星质量黑洞（BH）子系统存在时，GC的结构演化（核心和半质量半径）只取决于大质量原始双星的性质，因为它们影响BH双星（BBH）的数量，这主导了二进制加热过程。包括双白色矮双星（BWD）在内的低质量双星对动力学几乎没有影响。同时，只有来自BBH的引力波合并强烈地受到动力学相互作用的影响，而来自BWD的低质量合并在孤立环境（场）和GC中没有差异。低质量双星只有在大多数黑洞逃逸和轻恒星的核心坍缩发生后才变得重要。我们的结果表明，对于具有BH子系统的GC的N体模型，没有必要包括低质量的双星。这些双星可以通过使用独立的双星演化代码来单独研究。这种方式可以大大降低计算成本。
Observations found that star clusters contain a large fraction of binaries. Tight binaries are an important heating source that influences the long-term dynamical evolution of star clusters. However, due to the limitation ofN-body tool, previous theoretical modelling for globular clusters (GCs) by using directN-body simulations has not investigated how a large fraction of primordial binaries affect their long-term evolution. In this work, by using the high-performanceN-body code,petar, we carry out star-by-star models for intermediate massive GCs (N= 100 000) with the primordial binary fraction varying from 0 to 1. We find that when a stellar-mass black hole (BH) subsystem exists, the structural evolution of GCs (core and half-mass radii) only depends on the properties of massive primordial binaries, because they affect the number of BH binaries (BBHs), which dominate the binary heating process. Low-mass binaries including double white dwarf binaries (BWDs) have almost no influence on the dynamics. Meanwhile, only gravitational wave mergers from BBHs are strongly affected by dynamical interactions, while low-mass mergers from BWDs show no difference in the isolated environment (field) and in GCs. Low-mass binaries become important only after most BHs escape and the core collapse of light stars occurs. Our result suggests that forN-body modelling of GCs with a BH subsystem dominating binary heating, it is not necessary to include low-mass binaries. These binaries can be studied separately by using standalone binary stellar evolution codes. This way can significantly reduce the computing cost.