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

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Accurately modeling 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 semianalytic waveform models used in gravitational-wave data analysis. Previously, an effective precession spin χp was introduced to reduce the number of spin degrees of freedom. Here, we show that χp 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. To improve the higher-mode content, and in particular to facilitate an accurate incorporation of precession effects in the strong-field regime into waveform models, we introduce a new dimensional reduction through an effective precession spin vector, χ→, which takes into account precessing spin information from both black holes. We show that this adapted effective precession spin (i) mimics the precession dynamics of the fully precessing configuration remarkably well, (ii) captures the signature features of precession in higher-order modes, and (iii) reproduces the final state of the remnant black hole with high accuracy for the overwhelming majority of configurations. We demonstrate the efficacy of this two-dimensional precession spin in the strong-field regime, paving the path for meaningful calibration of the precessing sector of semianalytic waveform models with a faithful representation of higher-order modes through merger and the remnant black hole spin.

Original languageEnglish
Article number083022
JournalPhysical Review D
Issue number8
Publication statusPublished - 26 Apr 2021

Bibliographical note

Funding Information:
We thank Serguei Ossokine, Sascha Husa, Davide Gerosa, Juan Calderón Bustillo, Matthew Mould, Daria Gangardt, and our anonymous reviewer for useful discussions and comments. L. M. T. is supported by STFC, the School of Physics and Astronomy at the University of Birmingham, and the Birmingham Institute for Gravitational Wave Astronomy. P. S. acknowledges the Dutch Research Council (NWO) Veni Grant No. 680-47-460. This manuscript has the LIGO Document No. P2000509.

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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