Superradiance and stability of the novel 4D charged Einstein-Gauss-Bonnet black hole

TL;DR

This paper studies the superradiance and stability of a recently proposed 4D charged Einstein-Gauss-Bonnet black hole, revealing how the Gauss-Bonnet coupling affects superradiance and demonstrating the black hole's superradiant stability through quasinormal mode analysis.

Contribution

It provides the first detailed analysis of superradiance and stability for the novel 4D charged Einstein-Gauss-Bonnet black hole, including conditions for superradiant instability and quasinormal mode spectra.

Findings

Positive Gauss-Bonnet coupling enhances superradiance.

Negative coupling suppresses superradiance.

Black hole remains superradiant stable under studied conditions.

Abstract

We investigated the superradiance and stability of the novel 4D charged Einstein-Gauss-Bonnet black hole which is recently inspired by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)]. We found that the positive Gauss-Bonnet coupling consant $\alpha$ enhances the superradiance, while the negative $\alpha$ suppresses it. The condition for superradiant instability is proved. We also worked out the quasinormal modes (QNMs) of the charged Einstein-Gauss-Bonnet black hole and found that the real part of all the QNMs live beyond the superradiance condition and the imaginary parts are all negative. Therefore this black hole is superradiant stable. When $\alpha$ makes the black hole extremal, there are normal modes.