Coiffured Black Rings

TL;DR

This paper introduces a new class of supersymmetric black ring solutions with hair, allowing for arbitrary density profiles and violating black hole uniqueness, while maintaining regular horizons and smoothness in certain cases.

Contribution

It presents a novel family of black ring solutions with arbitrary hair functions, expanding the landscape of known black hole solutions and their uniqueness properties.

Findings

Largest known violation of black hole uniqueness.

Existence of solutions with arbitrary density profiles for electric fields.

Regular horizons with some solutions being infinitely differentiable.

Abstract

We describe a new type of hair on supersymmetric black string and black ring solutions, which produces the largest known violation of black hole uniqueness, parameterized by an arbitrary function and hence an infinite number of continuous parameters. The new solutions can have non-trivial density profiles for the electric fields along the horizon, and yet have a geometry that is regular, although generically not infinitely differentiable, at the horizon. Both neutral and charged probes can cross the horizon without experiencing divergent forces. We also find restricted examples, parameterized by a few arbitrary continuous parameters, where the charge densities fluctuate but the metric does not and hence is completely differentiable. Our new class of solutions owes its existence to a mechanism reminiscent of the Q-ball: in the simplest examples the metric has more symmetry than the matter that supports it.