Horizons in matter: black hole hair vs. Null Big Bang
Abstract
It is shown that only particular kinds of matter (in terms of the "radial" pressure to density ratio w) can coexist with Killing horizons in black-hole or cosmological space-times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter (w=-1, i.e., the cosmological constant or some its generalization) and matter with certain values of w between 0 and -1, in particular, a gas of disordered cosmic strings (w=-1/3). If the cosmological evolution starts from a horizon (the so-called Null Big Bang scenarios), this horizon can co-exist with vacuum matter and certain kinds of phantom matter with w≥ -3. It is concluded that normal matter in such scenarios is entirely created from vacuum.
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