Binary black hole mergers from hierarchical triples in open clusters

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 similar to 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. similar to 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.

Automated summary

Researchers explore the Lidov-Kozai-induced black hole mergers in open clusters and find a high merger rate density in the local Universe, with a significant proportion of mergers occurring during the cluster phase. This suggests that a substantial fraction of mergers from hierarchical triples occur within star-forming regions in spiral galaxies.