Stability of Non-Minimally Coupled Topological-Defect Boson Stars

TL;DR

This paper examines the stability of non-minimally coupled topological-defect boson stars, revealing that the most compact solutions are unstable, challenging their potential as stable astrophysical objects.

Contribution

It provides a stability analysis of non-minimally coupled boson star solutions, including those with shells of matter, using numerical and linear perturbation methods.

Findings

Highly compact solutions are unstable to radial perturbations.

Solutions with shells of bosonic matter are also unstable.

Most solutions are poor candidates for stable black hole mimickers.

Abstract

As shown by Marunovic and Murkovic, non-minimal d-stars, composite structures consisting of a boson star and a global monopole non-minimally coupled to the general relativistic field, can have extremely high gravitational compactness. In a previous paper we demonstrated that these ground-state stationary solutions are sometimes additionally characterized by shells of bosonic matter located far from the center of symmetry. In order to investigate the question of stability posed by Marunovic and Murkovic, we investigate the stability of several families of d-stars using both numerical simulations and linear perturbation theory. For all families investigated, we find that the most highly compact solutions, along with those solutions exhibiting shells of bosonic matter, are unstable to radial perturbations and are therefore poor candidates for astrophysically-relevant black hole mimickers or other highly compact stable objects.