Gravastars as Nontopological Solitons

TL;DR

This paper introduces solitonic gravastars, stable compact objects with a de Sitter interior and Schwarzschild exterior, formed by a coupled scalar, gauge, and Higgs fields within Einstein gravity, expanding the understanding of alternative compact objects.

Contribution

It presents new solutions for solitonic gravastars with photon spheres, combining scalar, gauge, and Higgs fields in a gravitational setting, and analyzes their mass and compactness properties.

Findings

Existence of stable solitonic gravastars with photon spheres.

Interior de Sitter and exterior Schwarzschild geometries connected by a surface layer.

Mass and compactness depend on system parameters.

Abstract

We investigate a coupled system consisting of a complex scalar field, a U(1) gauge field, a complex Higgs scalar field, and Einstein gravity. We present nontopological soliton star solutions in which the interior geometry is described by the de Sitter metric, the exterior by the Schwarzschild metric, and these two regions are attached by a spherical surface layer with a finite thickness. This structure is the same as the so-called gravastars, so we refer to these solutions as \lq solitonic gravastars\rq . We demonstrate that compact solitonic gravastars that possessing photon spheres can appear. Additionally, we study the mass and compactness of solitonic gravastars for various sets of parameters that characterize the system.