Eccentric binary black holes: A new framework for numerical relativity waveform surrogates

Mounting evidence indicates that some of the gravitational wave signals observed by the LIGO/Virgo/KAGRA observatories might arise from eccentric compact object binaries, increasing the urgency for accurate waveform models for such systems. While for non-eccentric binaries, surrogate models are efficient and accurate, the additional features due to eccentricity have posed a challenge. In this talk, I will discuss a new approach to construct numerical relativity surrogates for eccentric binaries. The crux of this approach is a radial-phase based reparameterization of the waveform, along with a novel technique to exploit the approximate periodicity with radial oscillations during the inspiral. We apply this procedure to the (2,2) mode for non-spinning black hole binaries, and demonstrate that the resulting surrogate, NRSurE_q4NoSpin_22, is able to faithfully reproduce the underlying numerical relativity waveforms, with maximum mismatches of 5×10^-4 and median mismatches of 2×10^-5. The approach is readily generalisable to spinning systems, paving the way for high-accuracy parameter estimation with eccentric models, a key ingredient for astrophysical inference and tests of general relativity.