Effect of eccentricity on searches for gravitational waves from coalescing compact binaries in ground-based detectors

Abstract

Inspiralling compact binaries are expected to circularize before their gravitational-wave signals reach the sensitive frequency band of ground-based detectors. Current searches for gravitational waves from compact binaries using the LIGO and Virgo detectors therefore use circular templates to construct matched filters. Binary formation models have been proposed which suggest that some systems detectable by the LIGO--Virgo network may have non-negligible eccentricity. We investigate the ability of the restricted 3.5 post-Newtonian order TaylorF2 template bank, used by LIGO and Virgo to search for gravitational waves from compact binaries with masses $M \le 35 M_\odot$, to detect binaries with non-zero eccentricity. We model the gravitational waves from eccentric binaries using the $x$-model post-Newtonian formalism proposed by Hinder \emph{et. al.} [I. Hinder, F. Hermann, P. Laguna, and D. Shoemaker, arXiv:0806.1037v1]. We find that small residual eccentricities ($e_0 \lesssim 0.05$ at 40 Hz) do not significantly affect the ability of current LIGO searches to detect gravitational waves from coalescing compact binaries with total mass $2 M_\odot < M < 15 M_\odot$. For eccentricities $e_0 \gtrsim 0.1$, the loss in matched filter signal-to-noise ratio due to eccentricity can be significant and so templates which include eccentric effects will be required to perform optimal searches for such systems.