Survey of four precessing waveform models for binary black hole systems

Abstract

Angular momentum and spin precession are expected to be generic features of a significant fraction of
binary black hole systems. As such, it is essential to have waveform models that faithfully incorporate
the effects of precession. Here, we assess how well the current state-of-the-art models achieve this for
waveform strains constructed only from the ℓ = 2 multipoles. Specifically, we conduct a survey on the
faithfulness of the waveform models SEOBNRV5PHM, TEOBRESUMS, IMRPHENOMTPHM, IMRPHENOMXPHM
to the numerical relativity (NR) surrogate NRSUR7DQ4 and to NR waveforms from the SXS catalog. The
former assessment involves systems with mass ratios up to 6 and dimensionless spins up to 0.8. The latter
employs 317 short and 23 long SXS waveforms. For all cases, we use reference inclinations of zero and
90°. We find that all four models become more faithful as the mass ratio approaches unity and when the
merger-ringdown portion of the waveforms are excluded. We also uncover a correlation between the
coprecessing (2, ±2) multipole mismatches and the overall strain mismatch. We additionally find that for
high inclinations, precessing (2, ±1) multipoles that are more faithful than their (2, ±2) counterparts, and
comparable in magnitude, improve waveform faithfulness. As a side note, we show that use of uniformly
filled parameter spaces may lead to an overestimation of precessing model faithfulness. We conclude our
survey with a parameter estimation study in which we inject two precessing SXS waveforms (at low and
high masses) and recover the signal with SEOBNRV5PHM, IMRPHENOMTPHM, and IMRPHENOMXPHM. As a
bonus, we present preliminary multidimensional fits to model unfaithfulness for Bayesian model selection
in parameter estimation studies.

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