Self energy in Kerr-Sen space-time incorporated to overspinning and overcharging problems

Previous attempts to overspin or overcharge Kerr-Sen black holes have been incomplete, as they neglect back-reaction effects. In this study, we incorporate the self-energy of perturbations, resulting from the induced increase in the angular velocity and the electrostatic potential of the event horizon, as described in a seminal work by Will. Our analysis demonstrates that Kerr-Sen black holes cannot be overspun or overcharged by perturbations that satisfy the null energy condition, within a comprehensive second-order framework that includes the self-energy of the perturbations.