Looking for spin precession and nutation in the gravitational-wave events*

Spin precession is the phenomena of a binary black hole (BBH) where the angle of the orbital plane tilts due to the entanglement of the orbiting objects' individual spins and the binary's angular momentum. Spin precession modulates the gravitational wave (GW) strain emitted by the binary. Being able to characterise spin precession in BBHs can be used to differentiate between formation channels or reveal insights about the different spin dynamics of a system as it inspirals. We investigate the current catalog of GW events by reformulating the publicly available parameter estimation prior and posteriors into distributions of five new phenomenological parameters. Unlike other parametrisations of spin precession, our parameters split the motion of the orbital angular momentum into its precession and nutation. We condition our priors on well-constrained parameters to establish dependencies and identify notable events. We find that events with high signal to noise ratios, low mass ratios and non-zero values of the effective spin parameter $\chi_{\rm eff}$ have precessional amplitudes constrained away from $0$. We find no evidence of nutation across the catalog, but expect this result to change as GW detectors become more sensitive.