Ancestral Spin Information in Gravitational Waves from Black Hole Mergers

TL;DR

This paper introduces a method to infer the properties of ancestral black holes from gravitational wave data, helping to explain the origins of heavy black holes observed in mergers.

Contribution

It presents a novel approach to estimate previous black hole generations' masses and spins using current merger data, considering hierarchical merger scenarios.

Findings

Assuming consistent black hole spins alters ancestral spin estimates.

Including spins does not significantly change ancestral mass distributions.

Application to GW190521 supports hierarchical merger hypothesis.

Abstract

The heaviest black holes discovered through gravitational waves have masses that are difficult to explain with current standard stellar models. This discrepancy may be due to a series of hierarchical mergers, where the observed black holes are themselves the products of previous mergers. Here we present a method to estimate the masses and spins of previous generations of black holes based on the masses and spins of black holes in a binary. Examining the merger GW190521, we find that assuming black hole spins that are consistent with those of merger remnants will alter the reconstructed ancestral spins when compared to results with uninformed priors. At the same time, the inclusion of black hole spins does not significantly affect the mass distributions of the ancestral black holes.