Measuring the eccentricity of GW170817 and GW190425

Understand

Two binary neutron star mergers, GW170817 and GW190425, have been detected by Advanced LIGO and Virgo.

• These signals were detected by matched-filter searches that assume the star's orbit has circularized by the time their gravitational-wave emission is observable.
• This suggests that their eccentricity is low, but full parameter estimation of their eccentricity has not yet been performed.
• We use gravitational-wave observations to measure the eccentricity of GW170817 and GW190425.