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

We present numerically-informed closed-form expressions for the dominant $(\mathrm{\ell },m)=(2,2)$ 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 ${\widehat{E}}_{\mathrm{e}\mathrm{f}\mathrm{f}}^{\mathrm{m}\mathrm{r}\mathrm{g}}$ and angular momentum $j_{\mathrm{m}\mathrm{r}\mathrm{g}}$. We further validate the post-merger non-circular waveform model by comparing it against simulations from the SXS catalog. Our models achieve mismatches around $\sim {10}^{-3}$, 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.