Inspiral-Merger-Ringdown waveform modeling to estimate spins of astrophysical black holes

Shrobana Ghosh

The LIGO-Virgo-KAGRA (LVK) collaboration has published about 90 gravitational wave observation since the first detection in 2015, majority of which have been from binary black holes. With such a statistically significant number of events it is possible to infer astrophysical distribution of black hole masses and spins. Of particular interest are spins(mis-aligned with the orbital angular momentum) of the component black holes in a binary, as they can shed light on the binary formation mechanism. Spin-misalignments of the component black holes leave their imprints on the waveform.One such modulation is due to an asymmetry between the +m and -m multipoles of the harmonic decomposition of the gravitational wave signal from the binary. This is not included in most signal models used in LVK analysis to date.I will present the first frequency-domain model of the asymmetry in the dominant co-precessing-frame signal multipole throughout inspiral, merger and ringdown. This model has been incorporated into the latest iteration of PHENOM family of precessing-binary models (PhenomXO4a) that will be used for analysing data from the fourth observing run (O4) of the LVK. I will briefly describe the features captured in PhenomXO4a and the prospect of spin measurements using this model.