Multimode Quasinormal Spectrum from a Perturbed Black Hole.

When two black holes merge, the late stage of gravitational wave emission is a superposition of exponentially damped sinusoids. According to the black hole no-hair theorem, this ringdown spectrum depends only on the mass and angular momentum of the final black hole. An observation of more than one ringdown mode can test this fundamental prediction of general relativity.

Posterior samples of the parameters of binary black holes from Advanced LIGO, Virgo's second observing run.

This paper presents a parameter estimation analysis of the seven binary black hole mergers-GW170104, GW170608, GW170729, GW170809, GW170814, GW170818, and GW170823-detected during the second observing run of the Advanced LIGO and Virgo observatories using the gravitational-wave open data. We describe the methodology for parameter estimation of compact binaries using gravitational-wave data, and we present the posterior distributions of the inferred astrophysical parameters. We release our samples of the posterior probability density function with tutorials on using and replicating our results presented in this paper.