Eccentricity estimation for five binary black hole mergers with higher-order gravitational wave modes

TL;DR

This paper evaluates the eccentricity of five binary black hole mergers detected by LIGO and Virgo using a comprehensive gravitational waveform model that includes higher-order modes, finding no strong evidence for eccentricity but noting parameter shifts.

Contribution

It introduces the use of the TEOBResumSGeneral model for eccentricity estimation across the full eccentricity range with higher-order modes, applied to real LIGO/Virgo data.

Findings

No strong evidence for eccentricity in the five analyzed events.

Marginal parameter shifts observed when allowing for eccentricity.

Model accounts for full eccentricity range and higher-order modes.

Abstract

The detection of orbital eccentricity for a binary black hole system via gravitational waves is a key signature to distinguish between the possible binary origins. The identification of eccentricity has been difficult so far due to the limited availability of eccentric gravitational waveforms over the full range of black hole masses and eccentricities. Here we evaluate the eccentricity of five black hole mergers detected by the LIGO and Virgo observatories for the first time using the TEOBResumSGeneral model. This model accounts for the full eccentricity range possible and incorporates higher-order gravitational wave modes critical to model emission from highly eccentric orbits. The binaries have been selected due to previous hints of eccentricity or due to their unusual mass and spin. While other studies found marginal evidence for eccentricity for some of these events, our analyses do not favor the incorporation of eccentricity compared to the quasi-circular case. While lacking the eccentric evidence of other analyses, we find our analyses marginally shifts the posterior in multiple parameters for several events when allowing eccentricity to be non-zero.