Is black-hole ringdown a memory of its progenitor?

TL;DR

This study shows that the gravitational-wave ringdown spectrum of merging black holes encodes information about the progenitors' masses and spins, enabling detailed parameter estimation and tests of general relativity.

Contribution

The paper demonstrates that black-hole ringdown modes contain signatures of the progenitors' properties and introduces Bayesian methods to extract this information from gravitational-wave data.

Findings

Progenitor masses and spins are encoded in the ringdown spectrum.

Bayesian inference can accurately measure progenitor parameters.

Results apply to precessing binaries, indicating broad applicability.

Abstract

We have performed an extensive numerical study of coalescing black-hole binaries to understand the gravitational-wave spectrum of quasi-normal modes excited in the merged black hole. Remarkably, we find that the masses and spins of the progenitor are clearly encoded in the mode spectrum of the ringdown signal. Some of the mode amplitudes carry the signature of the binary's mass ratio, while others depend critically on the spins. Simulations of precessing binaries suggest that our results carry over to generic systems. Using Bayesian inference, we demonstrate that it is possible to accurately measure the mass ratio and a proper combination of spins even when the binary is itself invisible to a detector. Using a mapping of the binary masses and spins to the final black hole spin, allows us to further extract the spin components of the progenitor. Our results could have tremendous implications for gravitational astronomy by facilitating novel tests of general relativity using merging black holes.