Confinement of exotic matter. I. Static solutions

TL;DR

This paper introduces a new type of boson star, called the ${\

Contribution

It presents the ${\\cal E}$-boson star, a novel configuration with exotic matter, showing unique distributions and properties, including surpassing the Buchdahl limit.

Findings

Existence of configurations with exotic matter and canonical matter in concentric spheres.

Shell-like distributions of canonical matter with exotic core.

Configurations exceeding the Buchdahl compactness limit.

Abstract

We present the ${\cal E}$-boson star: A novel configuration of a boson star with an exotic matter nucleus; the exotic matter being described by a real massive scalar field with self-interaction term and kinetic term of the opposite sign. The other scalar field is canonical, so that the system is similar to the material component of the quintom cosmological scenario. Considering the static spherical symmetric case, we obtain cases where both fields are distributed as concentric spheres, and others with the remarkable feature that the canonical matter is pushed outwards and obtain a shell-like distribution of the canonical field, with a nucleus of exotic matter at the center. We present global properties of such ${\cal E}$-boson stars and stress the differences that these configuration have with respect to the usual boson stars. In particular, we obtain cases where the compactness goes beyond the Buchdahl limit.