Scalarization of compact stars in the scalar-Gauss-Bonnet gravity

TL;DR

This paper investigates how scalar fields coupled to the Gauss-Bonnet invariant can induce scalar hair on horizonless compact reflecting stars, providing bounds on coupling parameters and analyzing their effects.

Contribution

It introduces a model for scalarization of compact stars via scalar-Gauss-Bonnet coupling, deriving bounds and numerical conditions for scalar hair formation.

Findings

Lower bounds on the coupling parameter for scalar hair formation

Discrete coupling parameters support scalar hairs outside stars

Model parameters influence the discrete coupling values

Abstract

We study scalarization of horizonless neutral compact reflecting stars. In our model, the scalar hair can be induced by the coupling of static scalar fields to the Gauss-Bonnet invariant. We analytically obtain lower bounds on the coupling parameter. Below the bound, the static scalar hair cannot form. And above the bound, we numerically get the discrete coupling parameter that can support scalar hairs outside stars. We also disclose effects of model parameters on the discrete coupling parameter.