Superradiance and instabilities in black holes surrounded by anisotropic fluids

Abstract

In this paper we analyze the propagation of a charged scalar field in a Reissner-Nordström black hole endowed with one anisotropic fluid that can play the role of a cosmological term for certain set of parameters. The evolution of a scalar wave scattering is examined giving rise to the same superradiant scattering condition as in the de Sitter case. In addition, an analysis of the modes coming from the application of quasinormal boundary conditions is presented. Some special cases displaying analytical solutions for the quasinormal frequencies are discussed. Moreover, the superradiant condition is adapted to the quasinormal problem triggering unstable modes, what is confirmed by our numerical analysis.

Superradiance and Stability of Kerr Black Hole Enclosed by Anisotropic Fluid Matter

“…Newly, for the charged Kiselev BH surrounded by these three types of anisotropic fluid matter, the superradiance and instability were analyzed[68]. In this regard, it is worth to mention that BH solution surrounded by anisotropic fluid matter, not only does not come from the Kiselev toy model, but also there is another metric[69,70] to address which is not our concern in this paper.…”