Fitting Multiple Quasinormal Modes to the Ringdown of GW190521

We report on the fitting of damped sinusoids to the ringdown of GW190521. We find that our analysis prefers fits which at least include both the 220 and 210 quasinormal modes, as opposed to other combinations of modes that have been presented previously in the literature. Our analysis notably suggests that the amplitudes of the 220 and 210 could be comparable: previous theoretical studies of ringdown quasinormal mode excitation do not predict such a large amplitude ratio, however most of the literature so far has focused on spin-aligned binary black-hole progenitors whose behavior may be substantially different from systems such as GW190521 which have evidence of significant spin misalignment. Additionally, we briefly discuss our efforts to analyze the ringdowns in the rest of the LIGO catalogue. The possibility of measuring the 210 and other fundamental modes in GW190521 and in other events has broad implications for our understanding of fundamental aspects of black-hole physics, and should enhance the power of tests of general relativity.