Newtonian and post-Newtonian binary neutron star mergers

TL;DR

This paper explores numerical simulations of neutron star mergers, focusing on gravitational wave signals and the transition from post-Newtonian to full relativistic models, providing insights into their dynamics and gravitational wave emission.

Contribution

It introduces Newtonian 3D simulations with radiation reaction effects and addresses the matching problem between post-Newtonian and general relativity formulations in neutron star modeling.

Findings

Radiation reaction effects influence gravitational wave luminosity.

Discontinuities at the matching surface are smoothed during relativistic evolution.

Proper slicing conditions improve the matching between models.

Abstract

We present two of our efforts directed toward the numerical analysis of neutron star mergers, which are the most plausible sources for gravitational wave detectors that should begin operating in the near future. First we present Newtonian 3D simulations including radiation reaction (2.5PN) effects. We discuss the gravitational wave signals and luminosity from the merger with/without radiation reaction effects. Second we present the matching problem between post-Newtonian formulations and general relativity in numerical treatments. We prepare a spherical, static neutron star in a post-Newtonian matched spacetime, and find that discontinuities at the matching surface become smoothed out during fully relativistic evolution if we use a proper slicing condition.