Superradiant scattering of massive scalar field due to magnetically charged rotating black hole

TL;DR

This paper investigates how magnetic charge in rotating black holes influences superradiant scattering of massive scalar fields, revealing enlarged amplification ranges and potential similarities to Kerr-Newman black holes.

Contribution

It introduces the study of superradiance in magnetically charged rotating black holes, highlighting the effects of magnetic charge on superradiant amplification and stability.

Findings

Magnetic charge affects the magnitude of superradiant amplification.

Magnetic charge enlarges the frequency range for superradiance.

Similar behaviors observed compared to Kerr-Newman black holes.

Abstract

Rotating black holes are well known to amplify the perturbing bosonic fields in certain parameter spaces. This phenomenon is popularly known as superradiance. In addition to rotation in the spacetime, charge plays a crucial role in the amplification process. In the present study, we have considered the spacetime of a magnetically charged rotating black hole emerging from the coupling of nonlinear electromagnetic field configuration to gravity. Due to this black hole spacetime, we have studied the scattering states of a massive scalar field and investigated the superradiant amplification process. We find that the magnetic charge of the spacetime affects the magnitude of the amplification and also significantly enlarges the allowed frequency ranges for which superradiance happens. In comparison, our analysis reveals that some of the behaviours are quite similar to what has been found in the case of the Kerr-Newmann black hole. Moreover, in specific parameter spaces, we observe exact similarities, which could imply a probable correspondence between the magnetically charged black hole and the Kerr-Newman black hole in certain scenarios. In addition to this, we have investigated the superradiant instability regime due to the massive potential barrier and also compared our results with that of the Kerr-Newmann black hole.