Binary Black Hole Mergers from Globular Clusters: Implications for Advanced LIGO

TL;DR

This paper investigates how dense stellar environments like globular clusters can produce binary black hole mergers at high rates, potentially detectable by Advanced LIGO, and suggests these mergers may be distinguishable by their mass.

Contribution

It provides a comprehensive analysis of black hole binary formation in globular clusters using realistic models, highlighting their significant contribution to gravitational wave detections.

Findings

Estimated detection rate of ~100 mergers per year from globular clusters.

Most cluster-formed binaries are more massive than field-formed ones.

Globular cluster mergers could dominate the overall black hole merger rate.

Abstract

The predicted rate of binary black hole mergers from galactic fields can vary over several orders of magnitude and is extremely sensitive to the assumptions of stellar evolution. But in dense stellar environments such as globular clusters, binary black holes form by well-understood gravitational interactions. In this letter, we study the formation of black hole binaries in an extensive collection of realistic globular cluster models. By comparing these models to observed Milky Way and extragalactic globular clusters, we find that the mergers of dynamically-formed binaries could be detected at a rate of ~100 per year, potentially dominating the binary black hole merger rate. We also find that a majority of cluster-formed binaries are more massive than their field-formed counterparts, suggesting that Advanced LIGO could identify certain binaries as originating from dense stellar environments.