On charged boson stars

TL;DR

This paper investigates charged boson stars, finding numerical solutions to Einstein-Maxwell equations coupled with a scalar field, identifying stability conditions, and analyzing physical properties like mass and charge distributions.

Contribution

It provides the first detailed numerical analysis of stable charged boson star configurations and their stability criteria within the Einstein-Maxwell-scalar framework.

Findings

Stable configurations exist only below a critical coupling constant.

Physical quantities reach maximum values at a critical scalar field at the origin.

Some configurations have positive binding energy, indicating potential stability.

Abstract

We study static, spherically symmetric, self-gravitating systems minimally coupled to a scalar field with U(1) gauge symmetry: charged boson stars. We find numerical solutions to the EinsteinMaxwell equations coupled to the relativistic Klein-Gordon equation. It is shown that bound stable configurations exist only for values of the coupling constant less than or equal to a certain critical value. The metric coefficients and the relevant physical quantities such as the total mass and charge, turn out to be in general bound functions of the radial coordinate, reaching their maximum values at a critical value of the scalar field at the origin. We discuss the stability problem both from the quantitative and qualitative point of view. Taking properly into account the electromagnetic contribution to the total mass, the stability issue is faced also following an indication of the binding energy per particle, verifying then the existence of configurations having positive binding energy: objects apparently bound can be unstable against small perturbations, in full analogy with what observed in the mass-radius relation of neutron stars.