Gravitational waves from eccentric binary neutron star mergers: Systematic biases and inadequacy of quasicircular templates

Abstract

The use of quasicircular waveforms in matched-filter analyses of signals from eccentric binary neutron star mergers can lead to biases in the source's parameter estimation. We demonstrate that significant biases can be present already for moderate eccentricities $e_{0} \gtrsim 0.05$ and signals detected by LIGO-Virgo-KAGRA with signal-to-noise ratio $\gtrsim 12$. We perform systematic Bayesian mock analyses of unequal-mass nonspinning binary neutron star signals up to eccentricities $e_0 \sim 0.1$ using quasicircular effective-one-body waveforms with spins. We find fractional signal-to-noise ratio losses up to tens of percent and up to 16$\sigma$ deviations in the inference of the chirp mass. The latter effect is sufficiently large to lead to an incorrect (and ambiguous) source identification. The inclusion of spin precession in the quasicircular waveform does not capture eccentricity effects. We conclude that high-precision observations with advanced (and next generation) detectors are likely to require standardized, accurate, and fast eccentric waveforms.