Gravitational wave signals from precessing binary black hole inspirals

Nearly 100 binary black hole mergers have been observed as gravitational wave (GW) signals by the LIGO-Virgo-KAGRA network. Astrophysical black holes are generally spinning, such that in binary black hole mergers, black hole spins and the orbital angular momentum of the binary need not be aligned. Dynamics such as precession and nutation are associated with these misalignments. The orbital angular momentum precessing in a cone centered around the total angular momentum causes modulations in the GW signal originating from coalescing binaries. We propose a geometrical toy model to quantify precession based on the hierarchy of orbital-precessional-radiation reaction timescales in coalescing binaries. By introducing precession parameters like the precession amplitude and the precession frequency, we investigate the waveforms generated by GW sources with different orbital orientations and sky locations. We establish the detectability of these parameters in the waveforms and effects of sky localizations of the source by calculating mismatches with a non-precessing signal. Mismatch, which quantifies the differences in the waveforms, helps in providing a relation for the distinguishability of a precessing signal from a non-precessing using the Lindblom criterion.