Condition for Superradiance in Higher-dimensional Rotating Black Holes

TL;DR

This paper demonstrates that superradiance modes always occur in radiation from higher-dimensional rotating black holes, providing a specific condition for these modes based on wave frequency and black hole rotation.

Contribution

It establishes the universal existence of superradiance modes in higher-dimensional rotating black holes and derives the precise condition for these modes using a Bekenstein argument.

Findings

Superradiance modes always exist in higher-dimensional rotating black holes.

The condition for superradiance is 0 < ω < mΩ for various waves.

The result applies to scalar, electromagnetic, and gravitational waves.

Abstract

It is shown that the superradiance modes always exist in the radiation by the $(4+n)$-dimensional rotating black holes. Using a Bekenstein argument the condition for the superradiance modes is shown to be $0 < \omega < m \Omega$ for the scalar, electromagnetic and gravitational waves when the spacetime background has a single angular momentum parameter about an axis on the brane, where $\Omega$ is a rotational frequency of the black hole and $m$ is an azimuthal quantum number of the radiated wave.