Publikace ÚTF

In our previous work [N. Gürlebeck and 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 nonlinear theory.