Quantum Criticality in Black Hole Scattering

TL;DR

This paper explores critical phenomena in black hole scattering described by the Teukolsky equation, revealing a conformal symmetry at extremal conditions and analyzing the dominant critical fluctuations across parameter ranges.

Contribution

It identifies a critical point in Kerr black hole scattering where conformal symmetry emerges and demonstrates the persistence of critical fluctuations away from this point.

Findings

Critical point exists at extremal black holes with superradiant bound

Conformal symmetry emerges at the critical point

Critical fluctuations dominate over a wide parameter range

Abstract

The Teukolsky equation describing scattering from Kerr black holes captures a few important effects in the process of binary mergers, such as tidal deformations and the decay of ringdown modes, thereby raising interest in the structure of its solutions. In this letter we identify critical phenomena emerging in the corresponding phase space. One special point exists in this phase space, where the black hole is extremal and the scattered wave lies exactly at the superradiant bound, at which the physics simplifies considerably. We provide an indirect realization of a conformal symmetry emerging at this configuration, which leads to its interpretation as a critical point. Away from the critical point conformal symmetry is broken, but it is shown that critical fluctuations continue to be dominant in a wide range of parameters and at finite black hole temperatures. As in quantum many-body systems, the physics in this regime is described exclusively by the temperature and a set of critical exponents, therefore leading to robust predictions that are unique to the Kerr metric.