Leveraging Ringdown to Infer Eccentricity in Binary Black Hole Coalescences

Can the ringdown of a binary black hole coalescence be used to determine if the binary orbit exhibited eccentricity rather than, or in addition to, spin precession? Distinguishing between both orbital effects in LIGO gravitational wave data is an ongoing challenge, due to observational degeneracies between the inspiral signatures of both phenomena. Further complicating the issue, binary formation channels which may lead to precessing and/or eccentric systems can also produce exceptionally massive black holes, which emit low-frequency inspiral content that is mostly obscured by instrumental noise. Thus, it is imperative to determine if data analyses can leverage merger-ringdown features unique to eccentricity or spin precession. We confirm through numerical relativity simulations that large and astrophysically implausible values of eccentricity are required to leave any imprint in the quasinormal mode amplitudes. By contrast, distinctive signatures of precession in the ringdown are more astrophysically achievable. It may be possible to use this information to make stronger observational statements about eccentricity and/or precession in current LIGO data.