Possible black universes in a brane world

TL;DR

This paper explores the possibility of black universe solutions within a brane world framework, demonstrating that such nonsingular black holes with expanding universes beyond the horizon can exist without phantom fields, using scalar fields with positive kinetic energy.

Contribution

It introduces a new class of black universe solutions in brane world models with standard scalar fields, extending previous phantom-based solutions to more physically plausible matter content.

Findings

Black universe solutions can be realized in brane worlds with normal scalar fields.

Explicit examples of such solutions are constructed.

These solutions have a Schwarzschild-like causal structure with a de Sitter universe beyond the horizon.

Abstract

A black universe is a nonsingular black hole where, beyond the horizon, there is an expanding, asymptotically isotropic universe. Such spherically symmetric configurations have been recently found as solutions to the Einstein equations with phantom scalar fields (with negative kinetic energy) as sources of gravity. They have a Schwarzschild-like causal structure but a de Sitter infinity instead of a singularity. It is attempted to obtain similar configurations without phantoms, in the framework of an RS2 type brane world scenario, considering the modified Einstein equations that describe gravity on the brane. By building an explicit example, it is shown that black-universe solutions can be obtained there in the presence of a scalar field with positive kinetic energy and a nonzero potential.