34,646 research outputs found
Black Holes in Gravity with Conformal Anomaly and Logarithmic Term in Black Hole Entropy
We present a class of exact analytic and static, spherically symmetric black
hole solutions in the semi-classical Einstein equations with Weyl anomaly. The
solutions have two branches, one is asymptotically flat and the other
asymptotically de Sitter. We study thermodynamic properties of the black hole
solutions and find that there exists a logarithmic correction to the well-known
Bekenstein-Hawking area entropy. The logarithmic term might come from non-local
terms in the effective action of gravity theories. The appearance of the
logarithmic term in the gravity side is quite important in the sense that with
this term one is able to compare black hole entropy up to the subleading order,
in the gravity side and in the microscopic statistical interpretation side.Comment: Revtex, 10 pages. v2: minor changes and to appear in JHE
Thermodynamic Geometry and Critical Behavior of Black Holes
Based on the observations that there exists an analogy between the
Reissner-Nordstr\"om-anti-de Sitter (RN-AdS) black holes and the van der
Waals-Maxwell liquid-gas system, in which a correspondence of variables is
, we study the Ruppeiner geometry, defined as
Hessian matrix of black hole entropy with respect to the internal energy (not
the mass) of black hole and electric potential (angular velocity), for the RN,
Kerr and RN-AdS black holes. It is found that the geometry is curved and the
scalar curvature goes to negative infinity at the Davies' phase transition
point for the RN and Kerr black holes.
Our result for the RN-AdS black holes is also in good agreement with the one
about phase transition and its critical behavior in the literature.Comment: Revtex, 18 pages including 4 figure
Holographic Thermodynamic on the Brane in Topological Reissner-Nordstr\"om de Sitter Space
We consider the brane universe in the bulk background of the topological
Reissner-Nordstr\"om de Sitter black holes. We show that the thermodynamic
quantities (including entropy) of the dual CFT take usual special forms
expressed in terms of Hubble parameter and its time derivative at the moment,
when the brane crosses the black hole horizon or the cosmological horizon. We
obtain the generalized Cardy-Verlinde formula for the CFT with an charge and
cosmological constant, for any values of the curvature parameter in the
Friedmann equations.Comment: 8 page
An Interacting Dark Energy Model for the Expansion History of the Universe
We explore a model of interacting dark energy where the dark energy density
is related by the holographic principle to the Hubble parameter, and the decay
of the dark energy into matter occurs at a rate comparable to the current value
of the Hubble parameter. We find this gives a good fit to the observational
data supporting an accelerating Universe, and the model represents a possible
alternative interpretation of the expansion history of the Universe.Comment: 6 pages, 2 figures, Phys. Rev. D versio
Thermodynamic Curvature of the BTZ Black Hole
Some thermodynamic properties of the Ba\~nados-Teitelboim-Zanelli (BTZ) black
hole are studied to get the effective dimension of its corresponding
statistical model. For this purpose, we make use of the geometrical approach to
the thermodynamics: Considering the black hole as a thermodynamic system with
two thermodynamic variables (the mass and the angular momemtum ), we
obtain two-dimensional Riemannian thermodynamic geometry described by positive
definite Ruppeiner metric. From the thermodynamic curvature we find that the
extremal limit is the critical point. The effective spatial dimension of the
statistical system corresponding to the near-extremal BTZ black holes is one.
Far from the extremal point, the effective dimension becomes less than one,
which leads to one possible speculation on the underlying structure for the
corresponding statistical model.Comment: 19 pages, LaTeX with revtex macro, 4 figures in eps file
The Cardy-Verlinde formula and entropy of Topological Reissner-Nordstr\"om black holes in de Sitter spaces
In this paper we discuss the question of whether the entropy of cosmological
horizon in Topological Reissner-Nordstr\"om- de Sitter spaces can be described
by the Cardy-Verlinde formula, which is supposed to be an entropy formula of
conformal field theory in any dimension. Furthermore, we find that the entropy
of black hole horizon can also be rewritten in terms of the Cardy-Verlinde
formula for these black holes in de Sitter spaces, if we use the definition due
to Abbott and Deser for conserved charges in asymptotically de Sitter spaces.
Our result is in favour of the dS/CFT correspondence.Comment: 6 pages, accepted for publication in IJMP
Thermodynamic of the Ghost Dark Energy Universe
Recently, the vacuum energy of the QCD ghost in a time-dependent background
is proposed as a kind of dark energy candidate to explain the acceleration of
the Universe. In this model, the energy density of the dark energy is
proportional to the Hubble parameter , which is the Hawking temperature on
the Hubble horizon of the Friedmann-Robertson-Walker (FRW) Universe. In this
paper, we generalized this model and choice the Hawking temperature on the
so-called trapping horizon, which will coincides with the Hubble temperature in
the context of flat FRW Universe dominated by the dark energy component. We
study the thermodynamics of Universe with this kind of dark energy and find
that the entropy-area relation is modified, namely, there is an another new
term besides the area term.Comment: 8 pages, no figure
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