Energy extraction from AdS black holes via superradiance

TL;DR

This paper demonstrates that energy can be extracted from rotating and charged AdS black holes through superradiance by applying suitable time-dependent boundary conditions, revealing a reversible energy extraction process in the dual thermal states.

Contribution

It characterizes superradiance in AdS black holes as an energy extraction process using boundary conditions, extending understanding of black hole thermodynamics in AdS spacetimes.

Findings

Energy can be extracted from Reissner-Nordström-AdS4 and Kerr-AdS4 black holes.

Energy extraction is achievable via time-dependent boundary conditions.

The process is reversible, preserving the total energy.

Abstract

Superradiance is known as a wave amplification process caused by rotating or charged black holes. We argue that the superradiance of stationary black holes in asymptotically AdS spacetimes can be characterized by the ability of energy extraction. Specifically, we demonstrate that energy can be extracted from Reissner-Nordstr\"{o}m-AdS$_4$ and Kerr-AdS$_4$ under appropriate time-dependent boundary conditions at conformal boundaries. This indicates that energy can be extracted from thermal states dual to these black holes by applying appropriate time-dependent sources. We also show that the energy extraction can be realized as a reversible process.