Hairy black resonators and the AdS$_4$ superradiant instability

TL;DR

This paper investigates the superradiant instability of Kerr-AdS black holes, revealing a two-stage process leading to multi-oscillating black holes close to hairy black resonators, with implications for dual quantum field theories.

Contribution

It introduces a detailed numerical study of the superradiant instability, identifying a new multi-oscillating black hole state close to hairy black resonators with non-unique hair.

Findings

Discovery of a two-stage superradiant instability process.

Identification of multi-oscillating black holes resembling hairy black resonators.

Evidence of spontaneous symmetry breaking and negative energy regions in the dual field theory.

Abstract

The superradiant instability of Kerr-AdS black holes is studied by numerically solving the full 3+1 dimensional Einstein equations. We find that the superradiant instability results in a two stage process with distinct initial and secondary instabilities. At the end of the secondary instability the geometry oscillates at several distinct fundamental frequencies -- a multi-oscillating black hole. The multi-oscillating black hole is remarkably close to a black resonator, albeit with a bit of gravitational hair. During the hairy black resonator epoch, the evolution of the horizon area is consistent with the exponential approach to a constant. By employing different seed perturbations in the initial Kerr-AdS geometry, we also demonstrate that the black resonator's hair is not unique. In the dual quantum field theory description, rotation invariance is spontaneously broken and the energy density is negative in some regions, signaling an exotic state of matter which does not relax to a stationary configuration.