Horizon structure of rotating Einstein-Born-Infeld black holes and shadow

Understand

We investigate the horizon structure of the rotating Einstein-Born-Infeld solution which goes over to the Einstein-Maxwell's Kerr-Newman solution as the Born-Infeld parameter goes to infinity ($\beta \rightarrow \infty$).

• We find that for a given $\beta$, mass $M$ and charge $Q$, there exist critical spinning parameter $a_{E}$ and $r_{H}^{E}$, which corresponds to an extremal Einstein-Born-Infeld black hole with degenerate horizons, and $a_{E}$ decreases and $r_{H}^{E}$ increases with increase in the Born-Infeld parameter $\beta$.
• While $a<a_{E}$ describe a non-extremal Einstein-Born-Infeld black hole with outer and inner horizons.
• Similarly, the effect of $\beta$ on infinite redshift surface and in turn on ergoregion is also included.