Rotating black holes pierced by a cosmic string

TL;DR

This paper investigates the complex interactions between rotating black holes and cosmic strings within the Abelian Higgs model, revealing new features like modified ISCO and phase transitions in the Kerr-string system.

Contribution

It demonstrates that rotation alters the backreaction of cosmic strings on black holes, leading to novel phenomena such as non-conical deficits and a gravitational Meissner effect.

Findings

Rotation modifies the string's backreaction, affecting black hole spacetime features.

Large black holes have pierced horizons, small ones exhibit flux expulsion.

Phase transition occurs in extremal black holes between flux penetration and expulsion.

Abstract

A rotating black hole threaded by an infinitely long cosmic string is studied in the framework of the Abelian Higgs model. We show that contrary to a common belief, in the presence of rotation the backreaction of the string does not induce a simple conical deficit. This leads to new distinct features of the Kerr--string system such as modified ISCO or shifted ergosphere, though these effects are likely outside the range of observational precision. For an extremal rotating black hole, the system exhibits a first-order phase transition for the gravitational Meissner effect: whereas the horizon of large black holes is pierced by the vortex, small black holes exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon. A brief review prepared for the MG14 Proceedings.