New effective precession spin for modeling multimodal gravitational waveforms in the strong-field regime

Understand

Accurately modelling the complete gravitational-wave signal from precessing binary black holes through the late inspiral, merger and ringdown remains a challenging problem.

• The lack of analytic solutions for the precession dynamics of generic double-spin systems, and the high dimensionality of the problem, obfuscate the incorporation of strong-field spin-precession information into semi-analytic waveform models used in gravitational-wave data analysis.
• Previously, an effective precession spin, $\chi_p$, was introduced to reduce the number of spin degrees of freedom.
• Here, we show that $\chi_p$ alone does not accurately reproduce higher-order multipolar modes, in particular the ones that carry strong imprints due to precession such as the $(2,1)$-mode.