Modified gravity in three dimensional metric-affine scenarios

TL;DR

This paper explores three-dimensional metric-affine gravity models with electrovacuum sources, revealing deviations from General Relativity and new features at finite distances, relevant for astrophysics and condensed matter analogs.

Contribution

It investigates modified gravity in 3D metric-affine frameworks with electrovacuum sources, highlighting deviations and novel features in specific theories like $f(R)$ and Born-Infeld gravity.

Findings

Deviations from GR near the center in $f(R)$ theories.

New features at finite distances in Born-Infeld gravity.

Properties of space-times with a cosmological constant discussed.

Abstract

We consider metric-affine scenarios where a modified gravitational action is sourced by electrovacuum fields in a three dimensional space-time. Such scenarios are supported by the physics of crystalline structures with microscopic defects and, in particular, those that can be effectively treated as bi-dimensional (like graphene). We first study the case of $f(R)$ theories, finding deviations near the center as compared to the solutions of General Relativity. We then consider Born-Infeld gravity, which has raised a lot of interest in the last few years regarding its applications in astrophysics and cosmology, and show that new features always arise at a finite distance from the center. Several properties of the resulting space-times, in particular in presence of a cosmological constant term, are discussed.