Quantum Treatment of Black Hole Superradiance

TL;DR

This paper provides a fully quantum description of black hole superradiance by quantizing a massive scalar field around a Kerr black hole, explaining particle production, cloud growth, and related phenomena within quantum field theory in curved spacetime.

Contribution

It introduces a canonical quantization approach for scalar fields around Kerr black holes, offering new insights into superradiance and associated quantum phenomena.

Findings

Quantum description of superradiance and particle production.

Cloud growth is independent of initial quantum state.

Analysis includes Hawking radiation and backreaction effects.

Abstract

Rotating black holes can form dense boson clouds through superradiant instability, making Kerr black holes a powerful probe of ultralight massive bosons. Previous studies of black hole superradiance have often treated bosonic fields classically, leaving open questions about how particles are produced and how the clouds grow over time. In this work, we canonically quantize a massive scalar field around a Kerr black hole, providing a fully quantum description of black hole superradiance. We show that the evolution of the particle number in the cloud, as well as the energy and angular momentum of the scalar field, can be consistently explained within the standard framework of quantum field theory in curved spacetime. Furthermore, we prove that the growth of the cloud occurs independently of the choice of initial state. We also explore several phenomena related to a massive scalar field in a rotating black hole spacetime, including Hawking radiation, adiabatic backreaction on the black hole spin, and the direction of level transitions in the presence of self-interactions of the field. Our analysis provides a consistent quantum-mechanical perspective that includes all these phenomena.