论文标题
年轻恒星簇中二元黑洞的动力学：群集质量和长期进化的影响
Dynamics of binary black holes in young star clusters: the impact of cluster mass and long-term evolution
论文作者
论文摘要
密集的恒星簇中的动力相互作用被认为是二元黑洞（BBHS）最有效的地层通道之一。在这里，我们提出了两个不同星团家庭的直接$ n- $车身模拟：低质量（$ \ sim {500-800} $ m $ _ \ odot $）和相对较高的质量星团（$ \ ge {5000} $ m $ _ $ _ \ odot $）。我们表明，低质量和高质量星团中BBH的形成通道极为不同，并导致两个完全不同的BBH合并种群。低质量簇宿主主要是由二进制进化而出生的低质量BBH，而高质量簇中的BBH则相对较大（chirp质量高达$ \ sim {100} $ m $ _ \ odot $），并且由动态交流驱动。潮汐破坏在非常短的时间尺度（$ \ lyssim {100} $ myr）上急剧消除了BBHS在低质量簇中的形成和动态演变，而高质量群集中的BBH则经过有效的动态硬化，直到我们的模拟结束（1.5 Gyr）。在高质量簇中，我们发现有8％的BBH在配对质量间隙中具有原发性质量，它们都是通过恒星碰撞出生的，而低质量簇中的质量间隙形式只有一个BBH。这些差异对于解释引力波源的形成通道至关重要。
Dynamical interactions in dense star clusters are considered one of the most effective formation channels of binary black holes (BBHs). Here, we present direct $N-$body simulations of two different star cluster families: low-mass ($\sim{500-800}$ M$_\odot$) and relatively high-mass star clusters ($\ge{5000}$ M$_\odot$). We show that the formation channels of BBHs in low- and high-mass star clusters are extremely different and lead to two completely distinct populations of BBH mergers. Low-mass clusters host mainly low-mass BBHs born from binary evolution, while BBHs in high-mass clusters are relatively massive (chirp mass up to $\sim{100}$ M$_\odot$) and driven by dynamical exchanges. Tidal disruption dramatically quenches the formation and dynamical evolution of BBHs in low-mass clusters on a very short timescale ($\lesssim{100}$ Myr), while BBHs in high-mass clusters undergo effective dynamical hardening until the end of our simulations (1.5 Gyr). In high-mass clusters we find that 8\% of BBHs have primary mass in the pair-instability mass gap, all of them born via stellar collisions, while only one BBH with primary mass in the mass gap forms in low-mass clusters. These differences are crucial for the interpretation of the formation channels of gravitational-wave sources.
