Einstein-Born-Infeld gravastar models, dark matter and accretion mechanisms

Gravastar models have recently been proposed as an alternative to black holes, mainly to avoid the problematic issues associated with event horizons and singularities. In this work, a regular variety of gravastar models within the context of Einstein Born Infeld (EBI) nonlinear electrodynamics are builded. These models presented here are truly regular in the sense that both the metric and its derivatives are continuous throughout spacetime, contrary to other cases in the literature where matching conditions are necessary in the interior and exterior regions of the event horizon. We investigated the accretion process for spherically symmetric spacetime geometries generated for a nonlinear electromagnetic field where the energy-momentum tensor has the same form that an anisotropic fluid that is the general EBI case. We analyze this procedure using the most general static spherically symmetric metric ansatz. In this theoretical context, we examined the accretion process for specific spherically symmetric compact configuration obtaining the accretion rates and the accretion velocities during the process and the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric.