Superradiance of rotating black holes surrounded by dark matter

TL;DR

This paper studies how dark matter surrounding rotating black holes affects superradiance, finding that dark matter suppresses superradiant amplification but does not alter the instability conditions.

Contribution

It provides the first detailed analysis of dark matter's impact on superradiance and instability in rotating black holes using asymptotic matching methods.

Findings

Dark matter suppresses superradiant amplification.

Dark matter does not affect superradiant instability conditions.

The energy extraction via superradiance is reduced in dark matter environments.

Abstract

In rotating black hole background surrounded by dark matter, we investigated the super-radiant phenomenon of massive scalar field and its associated instability.Using the method of asymptotic matching, we computed the amplification factor of scalar wave scattering to assess the strength of super-radiance. We discussed the influence of dark matter density on amplification factor in this black hole background. Our result indicates that the presence of dark matter has suppressive influence on black hole super-radiance. We also computed the net extracted energy to further support this result. Finally, we analyzed the super-radiant instability caused by massive scalar field using the black hole bomb mechanism and found that the presence of dark matter has no influence on the super-radiant instability condition.