Search for Eccentric Binary Neutron Star Mergers in the first and second observing runs of Advanced LIGO

TL;DR

This study searches for gravitational waves from eccentric binary neutron star mergers in LIGO data from 2015-2017, finds no new candidates, and sets upper limits on merger rates to inform future detector sensitivities.

Contribution

First search for eccentric binary neutron star mergers in LIGO's first two observing runs, establishing upper limits and informing future gravitational-wave detector expectations.

Findings

No significant eccentric binary neutron star candidates found beyond GW170817.

Set a 90% upper limit of ~1700 mergers Gpc^{-3} yr^{-1} for eccentricities less than 0.43.

Future detectors could constrain all current models of eccentric binary neutron star formation.

Abstract

We present a search for gravitational waves from merging binary neutron stars which have non-negligible eccentricity as they enter the LIGO observing band. We use the public Advanced LIGO data which covers the period from 2015 through 2017 and contains $\sim164$ days of LIGO-Hanford and LIGO-Livingston coincident observing time. The search was conducted using matched-filtering using the PyCBC toolkit. We find no significant binary neutron star candidates beyond GW170817, which has previously been reported by searches for binaries in circular orbits. We place a 90% upper limit of $\sim1700$ mergers $\textrm{Gpc}^{-3} \textrm{Yr}^{-1}$ for eccentricities $\lesssim 0.43$ at a dominant-mode gravitational-wave frequency of 10 Hz. The absence of a detection with these data is consistent with theoretical predictions of eccentric binary neutron star merger rates. Using our measured rate we estimate the sensitive volume of future gravitational-wave detectors and compare this to theoretical rate predictions. We find that, in the absence of a prior detection, the rate limits set by six months of Cosmic Explorer observations would constrain all current plausible models of eccentric binary neutron star formation.