Relativistic Structure, Stability and Gravitational Collapse of Charged Neutron Stars

TL;DR

This paper presents numerical models of charged neutron stars, analyzing their stability and collapse behavior, and finds that charge influences stability, with unstable stars collapsing or exploding, consistent with black hole thermodynamics and cosmic censorship.

Contribution

It introduces a set of numerical solutions for charged neutron stars and investigates their stability and collapse dynamics under various charge conditions.

Findings

Unstable stars collapse into black holes or explode when charge exceeds a threshold.

Stable stars oscillate and resist collapse despite perturbations.

Results support the third law of black hole thermodynamics and cosmic censorship.

Abstract

Charged stars have the potential of becoming charged black holes or even naked singularities. It is presented a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in hydrostatic equilibrium. The stellar models obtained are evolved forward in time integrating the Einstein-Maxwell field equations. It is assumed an equation of state of a neutron gas at zero temperature. The charge distribution is taken as been proportional to the rest mass density distribution. The set of solutions present an unstable branch, even with charge to mass ratios arbitrarily close to the extremum case. It is performed a direct check of the stability of the solutions under strong perturbations, and for different values of the charge to mass ratio. The stars that are in the stable branch oscillates and do not collapse, while models in the unstable branch collapse directly to form black holes. Stars with a charge greater or equal than the extreme value explode. When a charged star is suddenly discharged, it don't necessarily collapse to form a black hole. A non-linear effect that gives rise to the formation of an external shell of matter (see Ghezzi and Letelier 2005), is negligible in the present simulations. The results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.