A Surrogate Model of Gravitational Waveforms from Numerical Relativity Simulations of Precessing Binary Black Hole Mergers

TL;DR

This paper introduces NRSur4d2s, a novel surrogate model for precessing binary black hole gravitational waveforms derived directly from numerical relativity simulations, enhancing accuracy and efficiency for gravitational wave data analysis.

Contribution

The paper presents the first surrogate model for precessing binary black hole waveforms based on numerical relativity, extending reduced-order techniques without phenomenological assumptions.

Findings

Model achieves better agreement than existing models with typical mismatches of 10^{-3}.

Constructed a fast frequency domain surrogate suitable for parameter estimation.

Validated model with cross-validation on unseen numerical relativity waveforms.

Abstract

We present the first surrogate model for gravitational waveforms from the coalescence of precessing binary black holes. We call this surrogate model NRSur4d2s. Our methodology significantly extends recently introduced reduced-order and surrogate modeling techniques, and is capable of directly modeling numerical relativity waveforms without introducing phenomenological assumptions or approximations to general relativity. Motivated by GW150914, LIGO's first detection of gravitational waves from merging black holes, the model is built from a set of $276$ numerical relativity (NR) simulations with mass ratios $q \leq 2$, dimensionless spin magnitudes up to $0.8$, and the restriction that the initial spin of the smaller black hole lies along the axis of orbital angular momentum. It produces waveforms which begin $\sim 30$ gravitational wave cycles before merger and continue through ringdown, and which contain the effects of precession as well as all $\ell \in \{2, 3\}$ spin-weighted spherical-harmonic modes. We perform cross-validation studies to compare the model to NR waveforms \emph{not} used to build the model, and find a better agreement within the parameter range of the model than other, state-of-the-art precessing waveform models, with typical mismatches of $10^{-3}$. We also construct a frequency domain surrogate model (called NRSur4d2s_FDROM) which can be evaluated in $50\, \mathrm{ms}$ and is suitable for performing parameter estimation studies on gravitational wave detections similar to GW150914.