Universal Low-Energy Dynamics for Rotating Black Holes

TL;DR

This paper demonstrates that key features of low-energy black hole dynamics, including emission rates and quantum mass gaps, can be derived from semiclassical analysis of Kerr-Newman solutions, aligning with string theory predictions.

Contribution

It shows that essential low-energy black hole features can be obtained without string theory, using semiclassical methods on Kerr-Newman solutions.

Findings

Semiclassical emission rates match conformal field theory results.

Superradiant emission and greybody factors are consistent with CFT predictions.

Quantum mass gap for charge-Q black holes is derived without string theory.

Abstract

Fundamental string theory has been used to show that low energy excitations of certain black holes are described by a two dimensional conformal field theory. This picture has been found to be extremely robust. In this paper it is argued that many essential features of the low energy effective theory can be inferred directly from a semiclassical analysis of the general Kerr-Newman solution of supersymmetric four-dimensional Einstein-Maxwell gravity, without using string theory. We consider the absorption and emission of scalars with orbital angular momentum, which provide a sensitive probe of the black hole. We find that the semiclassical emission rates -including superradiant emission and greybody factors - for such scalars agree in striking detail with those computed in the effective conformal field theory, in both four and five dimensions. Also the value of the quantum mass gap to the lowest-lying excitation of a charge-$Q$ black hole, $E_{gap}=1/8Q^3$ in Planck units, can be derived without knowledge of fundamental string theory.