Dyonic Reissner-Nordstrom Black Holes and Superradiant Stability

TL;DR

This paper analytically determines the superradiant stability regime of dyonic Reissner-Nordstrom black holes with charged scalar perturbations, revealing the influence of magnetic fields on black hole stability.

Contribution

It provides the first analytical stability regime for dyonic black holes, highlighting the destabilizing effect of magnetic fields on superradiance.

Findings

Superradiant stability for 0<r_{-}/r_{+}<2/3

Magnetic coupling increases superradiant instability

Analytical effective potential analysis

Abstract

Black holes immersed in magnetic fields are believed to be important systems in astrophysics. One interesting topic on these systems is their superradiant stability property. In the present paper, we analytically obtain the superradiantly stable regime for the asymptotically flat dyonic Reissner-Nordstrom black holes with charged massive scalar perturbation. The effective potential experienced by the scalar perturbation in the dyonic black hole background is obtained and analyzed. It is found that the dyonic black hole is superradiantly stable in the regime $0<r_{-}/r_{+}<2/3$, where $r_\pm$ are the event horizons of the dyonic black hole. Compared with the purely electrically charged Reissner-Nordstrom black hole case, our result indicates that the additional coupling of the charged scalar perturbation with the magnetic field makes the black hole and scalar perturbation system more superradiantly unstable, which provides further evidence on the instability induced by magnetic field in black hole superradiance process.