Penrose Process Efficiency and Irreducible Mass in Rotating Einstein-Born-Infeld Black Holes with Nonlinear Electrodynamics

Abstract: We investigate the extraction of rotational energy from rotating Einstein-Born-Infeld (EBI) black holes, where nonlinear electrodynamics introduces a radius-dependent effective charge modifying the spacetime geometry. Focusing on neutral test particles in the equatorial plane, we derive analytic expressions for their kinematics and establish conditions for negative energy orbits essential to the Penrose process using the near-horizon limit and Wald inequality. We present a closed-form expression for maximal energy extraction efficiency as a function of spin, charge, and the Born-Infeld parameter $\beta$. Our numerical survey reveals that increasing charge and nonlinear Born-Infeld effects generally reduce horizon radius and ergoregion size, suppressing energy extraction efficiency compared to Kerr and often Kerr-Newman black holes. However, at certain spins and \$beta$, the EBI geometry can enhance efficiency beyond Kerr-Newman. We also compute the irreducible mass, showing how nonlinear electromagnetic dynamics reduce the horizon area and the associated entropy proxy. These results provide a unified picture linking nonlinear electrodynamics, horizon structure, and energy extraction efficiency across relevant parameters.