Inner structure of black holes in Eddington-inspired Born-Infeld gravity: The role of mass inflation

P. P. Avelino

Abstract
We investigate the interior dynamics of accreting black holes in Eddington-inspired Born-Infeld gravity using the homogeneous approximation and taking charge as a surrogate for angular momentum, showing that accretion can have an enormous impact on their inner structure. We find that, unlike in general relativity, there is a minimum accretion rate below which the mass inflation instability, which drives the center-of-mass streaming density to exponentially high values in an extremely short interval of time, does not occur. We further show that, above this threshold, mass inflation takes place inside black holes much in the same way as in general relativity, but is brought to a halt at an energy density which is, in general, much smaller than the fundamental energy density of the theory. We conjecture that some of these results may be a common feature of modified gravity theories in which significant deviations from general relativity manifest themselves at high densities.

Physical Review D
Volume 93
February 2016

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