Ultra-Spinning Gauged Supergravity Black Holes and their Kerr/CFT Correspondence

TL;DR

This paper constructs new ultra-spinning gauged supergravity black holes with noncompact horizons and demonstrates their compatibility with Kerr/CFT correspondence, showing the microscopic entropy matches the Bekenstein-Hawking entropy.

Contribution

It introduces exact ultra-spinning black hole solutions in gauged supergravity with noncompact horizons and analyzes their near horizon geometries and dual CFT properties.

Findings

Ultra-spinning black holes have noncompact horizons with finite area.

The ultra-spinning limit commutes with extremality and near horizon limits.

Microscopic entropy from dual CFT matches Bekenstein-Hawking entropy.

Abstract

Recently a new class of asymptotically AdS ultra-spinning black holes has been constructed with a noncompact horizon of finite area [1], in which the asymptotic rotation is effectively boosted to the speed of light. We employ this technique for four-dimensional $U(1)^4$ and five-dimensional $U(1)^3$ gauged supergravity black holes. The obtained new exact black hole solutions for both cases possess a noncompact horizon; their topologies are a sphere with two punctures. We then demonstrate that the ultra-spinning limit commutes with the extremality condition as well as the near horizon limit for both black holes. We also show that the near horizon extremal geometries of the resulting ultra-spinning gauged supergravity black holes lead to the well-known result which contains an AdS$_2$ throat. We then obtain the $[(d-1)/2]$ central charges of the dual CFTs. By assuming the Cardy formula, we show that despite the noncompactness of the horizon, microscopic entropy of the dual CFT is precisely equivalent to the Bekenstein-Hawking entropy.