Black Hole Superradiance in Dynamical Chern-Simons Gravity

TL;DR

This paper investigates how dynamical Chern-Simons gravity affects black hole superradiance, revealing additional modes and small corrections to scalar clouds around slowly rotating black holes, with implications for observations.

Contribution

It introduces the study of superradiance in dynamical Chern-Simons gravity, highlighting new modes and subtle effects on scalar clouds near rotating black holes.

Findings

Additional superradiant modes are excited in Chern-Simons gravity.

Chern-Simons contributions cause small angular corrections to scalar clouds.

Potential observable effects due to modified superradiance spectrum.

Abstract

Black hole superradiance provides a window into the dynamics of light scalar fields and their interactions close to a rotating black hole. Due to the rotation of the black hole, the amplitude of the scalar field becomes magnified, leading to a "black hole bomb" effect. Recent work has demonstrated that rotating black holes in dynamical Chern-Simons gravity possess unique structures, the "Chern-Simons caps," which may influence the behavior of matter near the black hole. Motivated by the presence of these caps, we study superradiance in dynamical Chern-Simons gravity in the context of a slowly rotating black hole. We find that additional modes are excited and contribute to the superradiance beyond what is expected for a Kerr black hole. Studying the superradiant spectrum of perturbations, we find that the Chern-Simons contributions give rise to small corrections to the angular dependence of the resulting scalar cloud. Finally, we comment on potential observable consequences and future avenues for investigation.