The Stability of Relativistic Neutron Stars in Binary Orbit

TL;DR

This paper investigates the stability of relativistic binary neutron stars in circular orbits, demonstrating they remain stable against collapse until reaching the innermost stable orbit.

Contribution

It applies turning point theorems to determine the stability limits of binary neutron stars in relativistic regimes, extending previous analyses.

Findings

Binary neutron stars are stable against collapse until the innermost stable orbit.

Stability against orbital plunge is confirmed up to the ISCO.

Theoretical methods effectively locate secular instability onset.

Abstract

We analyze the stability of relativistic, quasi-equilibrium binary neutron stars in synchronous circular orbit. We explore stability against radial collapse to black holes prior to merger, and against orbital plunge. We apply theorems based on turning points along uniformly rotating sequences of constant angular momentum and rest mass to locate the onset of secular instabilities. We find that inspiraling binary neutron stars are stable against radial collapse to black holes all the way down to the innermost stable circular orbit.