Superradiant (In)stability, Greybody Radiation, and Quasinormal Modes of Rotating Black Holes in non-linear Maxwell f (R) Gravity

Abstract

The research of superradiant instability in the realm of quantum gravity is a well-known topic, with many physicists and astronomers studying the potential impact it can have on gravitational waves, the structure of the universe, and spacetime itself. In this work, we investigate the superradiant (in)stability of a rotating black hole obtained from the nonlinear Maxwell $f(R)$ gravity theory. In this study, the evaluation of stability/instability is going to be based on non-existence and existence of magnetic field, when the magnetic field constant becomes $c_{4}=0$ and $c_{4}\neq 0$, respectively. The analyzes of greybody factor (GF) and quasinormal modes (QNMs) are investigated in the stationary black hole spacetime both in the absence and presence of the magnetic field parameter. To this end, we first consider the Klein-Gordon equation for the complex scalar field in the geometry of that rotating black hole. In the sequel, the obtained radial equation is reduced to a one-dimensional Schr\"{o}dinger-like wave equation with an effective potential energy. The effects of the nonlinear Maxwell $f(R)$ gravity theory parameters ($q$, $c$, and $c_{4}$) on the effective potential, GFs, and QNMs are thoroughly investigated. The obtained results show that even though the factors $q$, $c$, and $c_{4}$ all affect the effective potential, this phenomena, surprisingly, is not valid for the GFs and QNMs. With the proper graphics and tables, all outputs are depicted, tabulated, and interpreted.