论文标题
约束可使用Ligo-Virgo检测到的二进制黑洞的分层合并
Constraining hierarchical mergers of binary black holes detectable with LIGO-Virgo
论文作者
论文摘要
Ligo和处女座检测到的大多数二进制黑洞（BBH）合并可以通过恒星崩溃而形成的第一代合并来解释，而其他合并可能来自第二（或更高）一代的合并，即至少是一个黑洞（BHS）的层次合并。出现层次合并的主要条件是残留的BHS可以由宿主星群保留。我们提出了一个简单的公式，以估计星团中的层次合并速率。我们发现后者与保留概率成正比。此外，我们表明$ \ sim 2 \％$ $ bbh合并在核星团中（NSC）可能不是分层合并，而球状簇（GCS）的百分比仅为百分之十的百分之十。但是，GCS和NSC中的层次合并速率大致相同，即$ \ sim {\ Mathcal O（10^{ - 2}）}〜{\ rm gpc^{ - 3} 〜yr^yr^{ - 1}} $，因为BBH Merger在GC中比GCS更大。这表明，如果将Ligo-Virgo检测到的重力波事件被确定为层次合并，那么该合并同样源自GC或NSC。
Most of the binary black hole (BBH) mergers detected by LIGO and Virgo could be explained by first-generation mergers formed from the collapse of stars, while others might come from second (or higher) generation mergers, namely hierarchical mergers, with at least one of the black holes (BHs) being the remnant of a previous merger. A primary condition for the occurrence of hierarchical mergers is that the remnant BHs can be retained by the host star cluster. We present a simple formula to estimate the hierarchical merger rate in star clusters. We find this latter to be proportional to the retention probability. Further, we show that $\sim 2\%$ of BBH mergers in nuclear star clusters (NSCs) may instead be of hierarchical mergers, while the percentage in globular clusters (GCs) is only a few tenths of a percent. However, the rates of hierarchical merger in GCs and NSCs are about the same, namely of $\sim {\mathcal O(10^{-2})}~{\rm Gpc^{-3}~yr^{-1}}$, because the total BBH merger rate in GCs is larger than that in NSCs. This suggests that if a gravitational-wave event detected by LIGO-Virgo is identified as a hierarchical merger, then it is equally likely that this merger originated from a GC or an NSC.
