On the CFT duals for near-extremal black holes

TL;DR

This paper explores the near-horizon geometry of near-extremal Kerr-Newman-AdS-dS black holes, identifying their symmetries and showing that their entropy can be explained via a dual 2D conformal field theory using the Cardy formula.

Contribution

It explicitly derives the near-horizon geometry, identifies the asymptotic symmetries, and demonstrates the holographic duality with a 2D CFT for near-extremal black holes.

Findings

The near-horizon geometry has U(1)_L x U(1)_R isometries.

The asymptotic symmetry group includes a pair of Virasoro algebras.

The Cardy formula reproduces the black hole entropy.

Abstract

We consider Kerr-Newman-AdS-dS black holes near extremality and work out the near-horizon geometry of these near-extremal black holes. We identify the exact U(1)_L x U(1)_R isometries of the near-horizon geometry and provide boundary conditions enhancing them to a pair of commuting Virasoro algebras. The conserved charges of the corresponding asymptotic symmetries are found to be well defined and non-vanishing and to yield central charges c_L\neq0 and c_R=0. The Cardy formula subsequently reproduces the Bekenstein-Hawking entropy of the black hole. This suggests that the near-extremal Kerr-Newman-AdS-dS black hole is holographically dual to a non-chiral two-dimensional conformal field theory.