Charged black holes in Eddington-inspired Born-Infeld gravity: An in-depth analysis of the structure of spacetime geometry

Abstract

In this paper, we focus upon the behaviour of spacetime of charged black holes described by Eddington-inspired Born-Infeld (EiBI) gravity. With a static and spherically symmetric metric, we solve the ensuing field equations obtained from the EiBI-Maxwell action in the Palatini formalism. Consequently we carry out, for the first time, an in-depth analysis of the structure of spacetime geometry in several regions of the charged EiBI black hole. In particular, we consider the analytical behaviours of the metric coefficients and the Kretschmann scalar by probing their asymptotic nature {\em analytically} in different regions of the black hole spacetime, such as, near the center, in the intermediate region, and near the horizon, for both positive and negative EiBI coupling. These analyses give a thorough understanding of the nature of spacetime of EiBI-Maxwell black holes. In order to aide our understanding further, we solve the EiBI-Maxwell field equation numerically with different values of the parameters involved. We find close agreement between the analytical behaviours and those obtained from numerical integration of the EiBI-Maxwell field equation.

Figures (4)

• Figure 1: Radial profiles of the metric potential $f(r)$ and the Kretschmann scalar $\mathcal{K}(r)$ for the EiBI coupling $\kappa>0$.
• Figure 2: Radial profiles of the metric potential $f(r)$ and the Kretschmann scalar $\mathcal{K}(r)$ for the EiBI coupling $\kappa<0$.
• Figure 3: Radial profiles of the metric potential $f(r)h^2(r)$ for the cases $\kappa>0$ and $\kappa<0$.
• Figure 4: Parametric plots for the event horizon $R_{\rm EH}/M$.