On the Mass Ratio Distribution of Black Hole Mergers in Triple Systems

Understand

Observations have shown that the majority of massive stars, progenitors of black holes (BHs), have on average more than one stellar companion.

• In triple systems, wide inner binaries can be driven to a merger by the third body due to long-term secular interactions, most notably by the eccentric Lidov-Kozai effect.
• In this study, we explore the properties of BH mergers in triple systems and compare their population properties to those of binaries produced in isolation and assembled in dense star clusters.
• Using the same stellar physics and identical assumptions for the initial populations of binaries and triples, we show that stellar triples yield a significantly flatter mass ratio distribution from $q=1$ down to $q\sim0.3$ than either binary stars or dense stellar clusters, similar to the population properties inferred from the most recent catalog of gravitational-wave events, though we do not claim that all the observed events can be accounted for with triples.