# Massive and charged scalar field in Kerr-Newman spacetime: Absorption and superradiance

## TL;DR

This paper studies how scalar fields interact with Kerr-Newman black holes, analyzing absorption and superradiance phenomena through numerical and semi-analytical methods across different frequencies and angles.

## Contribution

It provides a comprehensive numerical analysis of scalar field absorption and superradiance in Kerr-Newman spacetime, including semi-analytical approximations and the effect of charge and incidence angles.

## Key findings

- Absorption cross sections vary with frequency and incidence angle.
- Semi-analytical formulas agree with numerical results.
- Charged scalar fields can undergo superradiant scattering.

## Abstract

We consider the propagation of a generic scalar field around a rotating and charged black hole. Using the partial wave method, we find, numerically, the total and partial absorption cross sections for different incidence angles. We investigate the low- and high-frequency limits, finding semi-analytical approximations for the absorption cross section, which we compare with our numerical results. Finally, we consider the superradiant regime, showing that, for charged fields, planar waves can be superradiantly scattered.