Kerr-Newman Black Hole Entropy and Soft Hair

TL;DR

This paper extends the soft hair and Virasoro algebra approach to Kerr-Newman black holes, successfully reproducing their Bekenstein-Hawking entropy by incorporating charge into the framework.

Contribution

It demonstrates how to modify the existing Kerr black hole entropy derivation to include charge, applying the Virasoro algebra and Cardy formula to Kerr-Newman black holes.

Findings

Reproduces Kerr-Newman entropy using Virasoro algebra and Cardy formula.

Shows minimal modification needed for charged black holes.

Supports the soft hair proposal for black hole entropy.

Abstract

Recently a set of diffeomorphisms were found which act nontrivially on the Kerr horizon and form a left-right pair of Virasoro algebras. Using the boundary formula for the associated central charge and assuming applicability of the Cardy formula to a putative dual CFT, the Bekenstein-Hawking entropy for the Kerr black hole was reproduced. In this paper, the addition of charge to the black hole is shown to require a minimal modification to this construction which then reproduces the Bekenstein-Hawking entropy for the Kerr-Newman black hole.