Highly eccentric non-spinning binary black hole mergers: quadrupolar post-merger waveforms

TL;DR

This paper develops accurate, numerically-informed models for the dominant post-merger gravitational waveforms from highly eccentric, non-spinning binary black hole mergers, validated against multiple simulation catalogs.

Contribution

It introduces multivariate polynomial models for the dominant waveform harmonic, incorporating eccentricity and merger parameters, enhancing waveform accuracy for parameter estimation.

Findings

Models achieve mismatches around 10^{-3}

Validated against RIT and SXS simulation catalogs

Effective for near-extreme eccentricities

Abstract

We present numerically-informed closed-form expressions for the dominant $(\ell,m)=(2,2)$ waveform harmonic of the post-merger emission from mergers of non-spinning binary black holes with comparable masses on highly eccentric orbits. Using 233 non-spinning eccentric simulations from the RIT catalog, we construct time-dependent complex quasinormal mode amplitudes via a Bayesian procedure. We build multivariate polynomial models, represented as functions of the symmetric mass ratio $\nu$ and two dynamics parameters evaluated at merger: the mass-rescaled effective energy $\hat{E}_{\mathrm{eff}}^{\mathrm{mrg}}$ and angular momentum $j_{\mathrm{mrg}}$. We further validate the post-merger non-circular waveform model by comparing it against simulations from the SXS catalog. Our models achieve mismatches around $\sim10^{-3}$, including for near-extreme eccentricities. The model can be directly combined with effective-one-body and phenomenological inspiral waveforms to produce accurate inspiral-merger-ringdown waveforms, essential for parameter estimation of both astrophysical and fundamental physics properties of the signals' sources.