Effect of eccentricity on binary neutron star searches in Advanced LIGO

TL;DR

This paper investigates how orbital eccentricity affects the detection of binary neutron star mergers in Advanced LIGO, finding that low eccentricities are negligible but high eccentricities require specialized search methods.

Contribution

It provides an analysis of eccentricity effects on BNS searches and identifies the eccentricity levels where circular search methods remain effective.

Findings

Eccentricities below 0.02-0.05 are negligible for detection.

Circular searches are effectual for low-eccentricity BNSs.

High eccentricity systems (up to 0.4) may require dedicated search strategies.

Abstract

Binary neutron stars (BNSs) are the primary source of gravitational waves for the Laser Interferometer Gravitational-Wave Observatory (LIGO) and its international partners Virgo and KAGRA. Current BNS searches target field binaries whose orbits will have circularized by radiation reaction before their gravitational waves enter the Advanced LIGO sensitive band at 15 Hz. It has been suggested that a population of BNSs may form by n-body interactions near supermassive black holes or in globular clusters and that these systems may have non-negligible eccentricity in the Advanced LIGO band. We show that for BNS systems with total mass of 2.4 (6.0) solar masses, the effect of eccentricity e < 0.02 (0.05) is negligible and a circular search is effectual for these binaries. For eccentricities up to e = 0.4, we investigate the selection bias caused by neglecting eccentricity in BNS searches. If such high eccentricity systems exist, searches that specifically target eccentric binaries will be needed in Advanced LIGO and Virgo.