Rotating Kaluza-Klein Black Holes

TL;DR

Rotating Kaluza-Klein Black Holes constructs a four-parameter family of regular four-dimensional black holes arising from five-dimensional vacuum gravity via Kaluza-Klein reduction, interpreted as rotating bound states of D0- and D6-branes with charges $Q$, $P$, angular momentum $J$, and mass $M$. Using a three-dimensional solution-generating approach based on $SO(3,3)$, the work yields a two-parameter class of regular solutions with vanishing Taub-NUT charge, and provides explicit expressions for the five-dimensional geometry and four-dimensional fields, together with relations between $(M,J,Q,P)$ and the solution parameters $(m,a,p,q)$. The paper analyzes duality properties, extremal limits and stability (including fragmentation bounds), thermodynamics with explicit entropy and first-law relations, charge quantization, and near-horizon structure, linking the macroscopic black hole data to potential microscopic CFT descriptions. A key result is the extremal entropy $S_{ m ext}=2\pi\\sqrt{(P^2Q^2)/G_4^2-J^2}$ and a detailed map to the D0-D6 brane system, highlighting stability due to angular momentum and suggesting avenues for a microscopic account within a (non-supersymmetric) conformal framework.

Abstract

All regular four-dimensional black holes are constructed in the theory obtained by Kaluza-Klein reduction of five-dimensional Einstein gravity. They are interpreted in string theory as rotating bound states of D0- and D6-branes. Conservation of angular momentum is important for the stability of the bound states. The thermodynamics, the duality symmetries, and the near-horizon limit are explored.