Measurability of precession and eccentricity for heavy binary-black-hole mergers

TL;DR

This study assesses the detectability of precession and eccentricity in heavy binary black hole mergers using injection analysis, highlighting challenges in parameter recovery for short signals and implications for interpreting gravitational wave events.

Contribution

It provides new insights into the measurability of precession and eccentricity effects in short gravitational wave signals from heavy black hole mergers, using advanced waveform models.

Findings

Total mass, mass ratio, and effective spin are well recovered.

Precession parameter recovery is limited and noise impacts short signals.

Eccentricity below 0.2 does not mimic precession in parameter estimation.

Abstract

Gravitational wave detections offer insights into the astrophysical populations of black holes in the universe and their formation processes. Detections of binaries consisting of black holes lying outside the bulk distribution of the astrophysical population are particularly intriguing. In this study, we perform an injection analysis within the intermediate-mass black hole range, utilizing the NR surrogate model NRSur7dq4 and a selection of NR waveforms from the SXS and RIT catalogues. Our investigation focuses on the detectability of precession and its potential degeneracy with eccentricity, especially for short signals with only a few cycles in band. While total mass, mass ratio, and $\chi_\mathrm{eff}$ are generally well recovered, the recovery of $\chi_\mathrm{p}$ is largely limited, and noise significantly impacts the recovery of some parameters for short signals. We also find that eccentricity lower than 0.2 is insufficient to mimic precession in parameter estimation when assuming a quasi-circular signal. Our results suggest that a certain degree of precession is necessary to produce evidence of high precession in parameter estimation, but it remains challenging to conclusively determine which effect is responsible for the high precession observed in events like GW190521. We emphasize the importance of caution when interpreting properties of a binary from short signals and highlight the potential benefits of future third generation detectors and eccentric waveform models for more exhaustive exploration of parameter space.