Plumbing the Abyss: Black Ring Microstates

TL;DR

This paper constructs smooth, horizonless microstate geometries for black rings that replicate their charges and angular momenta, revealing insights into black hole entropy and potential quantum critical points in the dual CFT.

Contribution

First explicit construction of smooth microstate geometries for black rings with the same charges and angular momenta, exploring their geometric and physical properties.

Findings

Microstate geometries can be arbitrarily deep when symmetry is broken.

Solutions suggest either stringy effects eliminate large regions or the CFT has quantum critical points.

Entropy elevators provide new tools for black hole entropy analysis.

Abstract

We construct the first smooth, horizonless ``microstate geometries'' that have the same charges, dipole charges and angular momenta as a BPS black ring whose horizon is macroscopic. These solutions have exactly the same geometry as black rings, except that the usual infinite throat is smoothly capped off at a very large depth. If the solutions preserve a U(1)x U(1) isometry, then this depth is limited by flux quantization but if this symmetry is broken then the throat can be made arbitrarily deep by tuning classical, geometric moduli. Interpreting these ``abysses'' (smooth microstate geometries of arbitrary depth) from the point of view of the AdS-CFT correspondence suggests two remarkable alternatives: either stringy effects can eliminate very large regions of a smooth low-curvature supergravity solution, or the D1-D5-P CFT has quantum critical points. The existence of solutions whose depth depends on moduli also enables us to define ``entropy elevators,'' and these provide a new tool for studying the entropy of BPS and near-BPS black holes.