A promising channel for producing binary black hole mergers is the Lidov–Kozai orbital resonance in hierarchical triple systems. While this mechanism has been studied in isolation, the distribution of such mergers in time and across star-forming environments is not well characterized. In this work, we explore Lidov–Kozai-induced black hole mergers in open clusters, combining semi-analytical and Monte Carlo methods to calculate merger rates and delay times for nine different population models. We predict a merger rate density of ∼1–10 Gpc−3 yr−1 for the Lidov–Kozai channel in the local Universe, and all models yield delay-time distributions in which a significant fraction of binary black hole mergers (e.g. ∼20–50 per cent in our baseline model) occur during the open cluster phase. Our findings suggest that a substantial fraction of mergers from hierarchical triples occur within star-forming regions in spiral galaxies.

中文翻译：

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疏散星团中分层三元组的二元黑洞合并

产生双黑洞合并的一个有希望的渠道是分层三重系统中的 Lidov-Kozai 轨道共振。虽然这种机制已经被孤立地研究过，但这种合并在时间上和在恒星形成环境中的分布并没有得到很好的表征。在这项工作中，我们探索了 Lidov-Kozai 在疏散星团中引起的黑洞合并，结合半解析和蒙特卡罗方法来计算九种不同人口模型的合并率和延迟时间。我们预测本地宇宙中 Lidov-Kozai 通道的合并率密度为 ∼1-10 Gpc-3 yr-1，并且所有模型都产生延迟时间分布，其中很大一部分二元黑洞合并（例如 20 –50% 在我们的基线模型中）发生在开放集群阶段。