Stability of electrically charged stars, regular black holes, quasiblack holes, and quasinonblack holes

TL;DR

This paper investigates the stability of various electrically charged compact objects, including stars and black holes, under radial perturbations, revealing conditions for their stability or instability using numerical analysis.

Contribution

It introduces a comprehensive stability analysis of charged fluid spheres with Reissner-Nordström exterior, including regular black holes and quasiblack holes, using the Chandrasekhar approach.

Findings

Stable charged stars and tension stars exist under certain conditions.

Regular black holes can be stable depending on the adiabatic index.

Quasiblack holes may be stable against radial perturbations.

Abstract

The stability of a class of electrically charged fluid spheres under radial perturbations is studied. Among these spheres there are regular stars, overcharged tension stars, regular black holes, quasiblack holes, and quasinonblack holes, all of which have a Reissner-Nordstr\"om exterior. We formulate the dynamical perturbed equations by following the Chandrasekhar approach and investigate the stability against radial perturbations through numerical methods. It is found that (i) under certain conditions that depend on the adiabatic index of the radial perturbation, there are stable charged stars and stable tension stars; (ii) also depending on the adiabatic index there are stable regular black holes; (iii) quasiblack hole configurations formed by, e.g., charging regular pressure stars or by discharging regular tension stars, can be stable against radial perturbations for reasonable values of the adiabatic index; (iv) quasinonblack holes are unstable against radial perturbations.