Vortices and black holes in dilatonic gravity

TL;DR

This paper analytically investigates black holes pierced by vortices in dilatonic gravity, revealing vortex-induced hair, flux expulsion in extremal cases, and conditions for smoothing singularities, with implications for black hole physics.

Contribution

It provides a detailed analytical study of vortex-black hole interactions in dilatonic gravity, including back-reaction effects and flux phenomena, extending understanding of black hole hair and singularity resolution.

Findings

Vortices can support long-range fields as black hole hair.

Extremal black holes exhibit flux expulsion for thick vortices.

Vortices can potentially smooth out singularities in dilatonic spacetimes.

Abstract

We study analytically black holes pierced by a thin vortex in dilatonic gravity for an arbitrary coupling of the vortex to the dilaton in an arbitrary frame. We show that the horizon of the charged black hole supports the long-range fields of the Nielsen-Olesen vortex that can be considered as black hole hair for both massive and massless dilatons. We also prove that extremal black holes exhibit a flux expulsion phenomenon for a sufficiently thick vortex. We consider the gravitational back-reaction of the thin vortex on the spacetime geometry and dilaton, and discuss under what circumstances the vortex can be used to smooth out the singularities in the dilatonic C-metrics. The effect of the vortex on the massless dilaton is to generate an additional dilaton flux across the horizon.