Binary Neutron Stars in General Relativity: Quasi-Equilibrium Models

TL;DR

This paper presents fully relativistic models of binary neutron stars in quasi-equilibrium, identifying the innermost stable orbit and analyzing how binary interaction affects neutron star mass limits.

Contribution

It introduces a method to compute initial data for binary neutron stars in general relativity, including the innermost stable orbit and mass effects.

Findings

Maximum allowed mass in close binaries exceeds that of isolated stars.

Sequences of constant rest mass are constructed for various separations.

The innermost stable circular orbit is identified and characterized.

Abstract

We perform fully relativistic calculations of binary neutron stars in quasi-equilibrium circular orbits. We integrate Einstein's equations together with the relativistic equation of hydrostatic equilibrium to solve the initial value problem for equal-mass binaries of arbitrary separation. We construct sequences of constant rest mass and identify the innermost stable circular orbit and its angular velocity. We find that the quasi-equilibrium maximum allowed mass of a neutron star in a close binary is slightly larger than in isolation.