Neutral and charged matter in equilibrium with black holes
Abstract
We study the conditions of a possible static equilibrium between spherically symmetric, electrically charged or neutral black holes and ambient matter. The following kinds of matter are considered: (1) neutral and charged matter with a linear equation of state p_r = w\rho (for neutral matter the results of our previous work are reproduced), (2) neutral and charged matter with p_r \sim \rho^m, m > 1, and (3) the possible presence of a "vacuum fluid" (the cosmological constant or, more generally, anything that satisfies the equality T^0_0 = T^1_1 at least at the horizon). We find a number of new cases of such an equilibrium, including those generalizing the well-known Majumdar-Papapetrou conditions for charged dust. It turns out, in particular, that ultraextremal black holes cannot be in equilibrium with any matter in the absence of a vacuum fluid; meanwhile, matter with w > 0, if it is properly charged, can surround an extremal charged black hole.
Keywords
Cite
@article{arxiv.1107.4701,
title = {Neutral and charged matter in equilibrium with black holes},
author = {K. A. Bronnikov and O. B. Zaslavskii},
journal= {arXiv preprint arXiv:1107.4701},
year = {2013}
}
Comments
12 pages, no figures, final version published in PRD