Fast frequency-domain phenomenological modeling of eccentric aligned-spin binary black holes

TL;DR

This paper introduces IMRPhenomXE, a fast frequency-domain waveform model for eccentric aligned-spin binary black holes, extending existing models to include eccentricity effects and validated against numerical relativity data.

Contribution

The paper presents the first efficient frequency-domain eccentric waveform model for aligned-spin binary black holes, extending the quasi-circular IMRPhenomXAS model to eccentric orbits.

Findings

IMRPhenomXE achieves less than 3% unfaithfulness for 72% of low-eccentricity simulations.

The model outperforms existing eccentric waveform models in speed.

IMRPhenomXE is robust and suitable for gravitational-wave data analysis.

Abstract

We present the IMRPhenomXE frequency-domain phenomenological waveform model for the dominant mode of inspiral-merger-ringdown non-precessing binary black holes in elliptical orbits. IMRPhenomXE extends the quasi-circular IMRPhenomXAS waveform model for the dominant $(\ell, |m|) =$ (2,2) modes to eccentric binaries. For the inspiral part, orbit-averaged equations of motion within the quasi-Keplerian parametrization up to third post-Newtonian order, including spin effects, are evolved, and the waveform modes are computed using the stationary phase approximation on eccentricity expanded expressions up to $\mathcal{O}(e^{12})$. The model assumes circularization at merger-ringdown, where it adopts the underlying quasicircular IMRPhenomXAS baseline. We show that IMRPhenomXE reduces to the accurate IMPhenomXAS model in the quasi-circular limit. Compared against 186 public numerical relativity waveforms from the Simulating eXtreme Spacetimes catalog with initial eccentricities up to $~0.8$, IMRPhenomXE provides values of unfaithfulness below $3\%$ for $72\%$ of simulations with initial eccentricities below 0.4. For larger eccentricities, the unfaithfulness degrades up to $\gtrsim 10\%$ due to the underlying small eccentricity expansions and additional modelling approximations. In terms of speed, IMRPhenomXE outperforms any of the existing inspiral-merger-ringdown eccentric waveform models. We demonstrate the efficiency, robustness, and modularity of IMRPhenomXE through injections into zero noise and parameter-estimation analyses of gravitational-wave events, showing that IMRPhenomXE is a ready-to-use waveform model for gravitational-wave astronomy in the era of rapidly growing event catalogs.