Black hole superradiance in the presence of Lorentz symmetry violation

In this paper we consider the massive scalar perturbation on the top of a small spinning-like black hole in context of Einstein-bumblebee modified gravity in order to probe the role of spontaneous Lorentz symmetry breaking on the superradiance scattering and corresponding instability. We show that at the low-frequency limit of the scalar wave the superradiance scattering will be enhanced with the Lorentz-violating parameter alpha < 0 and will be weakened with alpha > 0. Moreover, by addressing the black hole bomb issue, we extract an improved bound in the instability regime indicating that alpha < 0 increases the parameter space of the scalar field instability, while alpha > 0 decreases it.

Automated summary

This study investigates the massive scalar perturbation on a small spinning black hole in the context of Einstein-bumblebee modified gravity, to examine the impact of spontaneous Lorentz symmetry breaking on superradiance scattering and instability. The results show that superradiance scattering is enhanced with alpha < 0 and weakened with alpha > 0 in the low-frequency limit of the scalar wave. Additionally, analysis of the black hole bomb problem reveals that alpha < 0 expands the parameter space of scalar field instability, while alpha > 0 decreases it.