Eddington-inspired Born-Infeld gravity. Phenomenology of non-linear gravity-matter coupling

TL;DR

This paper explores Eddington-inspired Born-Infeld gravity, a non-linear modification of gravity that prevents singularities in astrophysical phenomena, and analyzes its implications for stellar objects and gravitational collapse.

Contribution

It provides a comprehensive analysis of the phenomenology of this modified gravity, including numerical simulations of collapse and the properties of compact stars.

Findings

Collapse results in regular pressureless stars instead of singularities

No Chandrasekhar limit for non-relativistic white dwarfs in this theory

Existence of an upper mass bound for relativistic compact stars

Abstract

Viable corrections to the matter sector of Poisson's equation may result in qualitatively different astrophysical phenomenology, for example the gravitational collapse and the properties of compact objects can change drastically. We discuss a class of modified non-relativistic theories and focus on a relativistic completion, Eddington-inspired Born-Infeld gravity. This recently proposed theory is equivalent to General Relativity in vacuum, but its non-trivial coupling to matter prevents singularities in early cosmology and in the non-relativistic collapse of non-interacting particles. We extend our previous analysis, discussing further developments. We present a full numerical study of spherically symmetric non-relativistic gravitational collapse of dust. For any positive coupling, the final state of the collapse is a regular pressureless star rather than a singularity. We also argue that there is no Chandrasekhar limit for the mass of non-relativistic white dwarf in this theory. Finally, we extend our previous results in the fully relativistic theory by constructing static and slowly rotating compact stars governed by nuclear-physics inspired equations of state. In the relativistic theory, there exists an upper bound on the mass of compact objects, suggesting that black holes can still be formed in the relativistic collapse.