Sufficient conditions for unbounded superradiance in black hole spacetimes sourced by nonlinear electrodynamics

Résumé : Considering the propagation of massive charged test scalar fields in the vicinity of electrically charged black hole (BH) solutions based on the nonlinear electrodynamics (NED) framework, we derive sufficient conditions to have an unbounded superradiant regime, with the corresponding total absorption cross section being negative and unbounded from below. We also discuss some possible general conditions that the NED electrical source associated with the geometry has to satisfy to trigger an unbounded superradiance. Our results apply to a broad family of electrically charged BH solutions (regular and singular) derived in the framework of NED minimally coupled to general relativity.