Black holes and stars in the minimal theory of massive gravity

TL;DR

This paper demonstrates that solutions in general relativity, including black holes and stars, also exist in the minimal theory of massive gravity without strong coupling issues, aligning with GR predictions at observable scales.

Contribution

It introduces black hole and star solutions in the minimal theory of massive gravity that match GR solutions and are free from strong coupling problems, extending phenomenological analysis to shorter scales.

Findings

Solutions of GR are also solutions of MTMG's self-accelerating branch.

Black hole and star solutions in MTMG are free from strong coupling issues.

Parametrized post-Newtonian parameters are identical to GR, i.e., unity.

Abstract

In this letter, we show that any solution of general relativity (GR) that can be rendered spatially flat by a coordinate change is also a solution of the self-accelerating branch of the minimal theory of massive gravity (MTMG), with or without matter. We then for the first time obtain black hole and star solutions in a theory of massive gravity that agree with the corresponding solutions in GR and that are free from strong coupling issues. This in particular implies that the parametrized post-Newtonian parameters $\beta^{\rm PPN}$ and $\gamma^{\rm PPN}$ are unity, as in GR. We further show how these solutions can be embedded in a cosmological setting. While cosmological scales have already been considered in previous works, this is the first study of the phenomenology at shorter scales of the self-accelerating branch of MTMG.