Abstract
In this paper we find analytical expressions for thermodynamic
quantities of scalar (tensor) and vector unparticle static black holes.
We also find rotating solutions to these systems and analyse their
thermodynamics. First we consider the static case with a spherically
symmetric source for both the vector and scalar (tensor) unparticles. We
obtain thus analytical expressions to the principal thermodynamic
quantities: Hawking temperature, entropy, heat capacity and free energy.
For the scalar (tensor) case we find that the black hole presents a
residual value for the entropy when its radius goes to zero but the
other thermodynamic quantities give, for any horizon radius, a
thermodynamically unstable behavior similar to the standard black hole.
For the vector case we find a richer structure in the region in which
the horizon radius is less than the characteristic length of the
unparticle theory. We identify a phase transition and a region where the
black hole can be thermodynamically stable. Following, we show that the
mentioned modifications in the standard gravity are formally similar to
those ones present in the black holes with quintessence. With this we
also show, notwithstanding, that the unparticles cannot be a source of
quintessence. By using this similarity we find two different rotating
solutions to the unparticle black holes based on works by Ghosh and
Toshmatov et al.. For both cases we compute the Hawking temperature and
in the ungravity dominated regime we find, as in the static cases, a
fractalization of the event horizon. For the Gosh-like solution the
fractal dimension depends on the polar angle and on the rotation of the
source. For the Toshmatov-like one it is equal to the static case and
therefore the fractalization is not dependent on the rotation of the
source.
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