Targeted Numerical Relativity Surrogate Waveform Model for GW190814

The recent detection of GW190814 highlights the need for reliable, high-accuracy gravitational waveform templates for binary black holes of high mass ratios. We describe NRHybSur2dq15, a surrogate model for hybridized, non-precessing numerical relativity (NR) waveforms, extending the previously explored mass ratio ranges. In this model, we train the surrogate over two parameters: the mass ratio, $q\in[1,15]$, and the spin of the higher-mass black hole, $\left|\chi^1_z\right|\leq 0.8$. For the training, we use hybrid waveforms generated from the NR simulations. The new surrogate model reproduces the hybrid waveforms with reasonable mismatches over the entire LIGO band for stellar-mass binaries. The surrogate model also is quite robust to extrapolations of the parameters. Finally, we use templates generated from the surrogate model for parameter estimation of GW190814.