Conformally flat, quasi-circular numerical simulations of the gravitational wave chirp from binary neutron star merger GW170817

TL;DR

This paper presents relativistic numerical simulations of binary neutron star mergers, validating the conformally flat approximation and exploring how gravitational wave signals depend on the nuclear equation of state, aiding in constraining dense matter properties.

Contribution

It introduces a calibration of the quasi-circular approximation for neutron star mergers and demonstrates how gravitational wave signals can constrain the nuclear equation of state.

Findings

Validation of the conformally flat approximation for GW170817

Dependence of gravitational wave chirp on the nuclear equation of state

Establishment of an efficient method to constrain dense matter properties

Abstract

The first detection of gravitational waves from the binary neutron star merger GW170817 by the LIGO-Virgo Collaboration has provided fundamental new insights into the astrophysical site for r-process nucleosynthesis and on the nature of dense neutron-star matter. The detected gravitational wave signal depends upon the tidal distortion of the neutron stars as they approach merger. We report on relativistic numerical simulations of the approach to binary merger in the conformally flat, quasi-circular orbit approximation. We show that this event serves as a calibration to the quasi-circular approximation and a confirmation of the validity of the conformally flat approximation to the three-metric. We then examine how the detected chirp depends upon the adopted equation of state. This establishes a new efficient means to constrain the nuclear equation of state in binary neutron star mergers.