Binary-Induced Gravitational Collapse: A Trivial Example

TL;DR

This paper introduces a simple relativistic model demonstrating how a stable compact object can become dynamically unstable due to tidal forces in a binary system, challenging existing stability assumptions.

Contribution

It provides a minimal model showing that relativistic tidal interactions can induce collapse, questioning the adequacy of current stability analyses for binary neutron stars.

Findings

Relativistic tidal forces can destabilize stable compact objects.

First order post-Newtonian treatments may be insufficient.

Binary stability analyses might need revision.

Abstract

We present a simple model illustrating how a highly relativistic, compact object which is stable in isolation can be driven dynamically unstable by the tidal field of a binary companion. Our compact object consists of a test-particle in a relativistic orbit about a black hole; the binary companion is a distant point mass. Our example is presented in light of mounting theoretical opposition to the possibility that sufficiently massive, binary neutron stars inspiraling from large distance can collapse to form black holes prior to merger. Our strong-field model suggests that first order post-Newtonian treatments of binaries, and stability analyses of binary equilibria based on orbit-averaged, mean gravitational fields, may not be adequate to rule out this possibility.