The Meissner Effect for axially symmetric charged black holes

TL;DR

This paper extends the understanding of the black hole Meissner effect to charged, non-idealized horizons, demonstrating it as a fundamental property even in complex, non-linear scenarios.

Contribution

It generalizes the Meissner effect to charged black holes with less restrictive horizon conditions, including pierced horizons and non-time-independent geometries.

Findings

The Meissner effect persists for charged black holes.

It applies to almost isolated horizons with non-spherical topology.

The effect holds in full non-linear gravitational theories.

Abstract

In our previous work [N. G\"urlebeck, M. Scholtz, Phys. Rev. D 95 064010 (2017)], we have shown that electric and magnetic fields are expelled from the horizons of extremal, stationary and axially symmetric uncharged black holes; this is called the Meissner effect for black holes. Here, we generalize this result in several directions. First, we allow that the black hole carries charge, which requires a generalization of the definition of the Meissner effect. Next, we introduce the notion of almost isolated horizons, which is weaker than the usual notion of isolated horizons, since the geometry of the former is not necessarily completely time-independent. Moreover, we allow the horizon to be pierced by strings, thereby violating the usual assumption on the spherical topology made in the definition of the weakly isolated horizon. Finally, we spell out in detail all assumptions entering the proof and show that the Meissner effect is an inherent property of black holes even in full non-linear theory.