CRA seminar (Jonathan Blackman)

Title: Surrogate models of gravitational waveforms from numerical relativity simulations of black hole mergers

Abstract: GW150914 was the first detection of gravitational waves from a binary black hole merger, bringing us into the era of gravitational wave astronomy. From such gravitational wave detections, we can put constraints on deviations from general relativity (GR), as well as measure the masses and spins of the black holes involved in the merger. Such measurements require knowledge of the gravitational waveforms predicted by GR for all relevant masses and spins. Numerical relativity (NR) simulations are now sufficiently robust that we can accurately simulate binary black hole mergers and obtain the waveform for all but the most extreme parameters, but they are too computationally expensive for a dense coverage of the parameter space. The effective-one-body model and phenomenological waveform models agree well with NR for the parameters of GW150914, but could be insufficiently accurate for estimating the parameters of a loud gravitational wave detection in other regions of the parameter space. NR surrogate models attempt to rapidly and accurately interpolate the waveforms from a set of NR simulations over a subset of parameter space. Using the Spectral Einstein Code (SpEC), we have built NR surrogate models for non-spinning binaries with mass ratios up to 10, and for spinning precessing binaries with a restricted spin direction on the smaller black hole. They typically perform an order of magnitude better than other waveform models when compared to NR waveforms which were not included in the surrogate training set, and can be used in gravitational wave parameter estimation.