48 research outputs found
Thermodynamics and evaporation of the noncommutative black hole
We investigate the thermodynamics of the noncommutative black hole whose
static picture is similar to that of the nonsingular black hole known as the de
Sitter-Schwarzschild black hole. It turns out that the final remnant of
extremal black hole is a thermodynamically stable object. We describe the
evaporation process of this black hole by using the noncommutativity-corrected
Vaidya metric. It is found that there exists a close relationship between
thermodynamic approach and evaporation process.Comment: 16 pages, 6 figures, added references, to appear in JHE
Absorption cross section in Lifshitz black hole
We derive the absorption cross section of a minimally coupled scalar in the
Lifshitz black hole obtained from the new massive gravity. The absorption cross
section reduces to the horizon area in the low energy and massless limit of
s-wave mode propagation, indicating that the Lifshitz black hole also satisfies
the universality of low energy absorption cross section for black holes.Comment: 13 pages, 1 figure, version to appear in EPJ
Extremal black holes in the Ho\v{r}ava-Lifshitz gravity
We study the near-horizon geometry of extremal black holes in the
Ho\v{r}ava-Lifshitz gravity with a flow parameter . For ,
near-horizon geometry of extremal black holes are AdS with
different radii, depending on the (modified) Ho\v{r}ava-Lifshitz gravity. For
, the radius of is negative, which means
that the near-horizon geometry is ill-defined and the corresponding
Bekenstein-Hawking entropy is zero. We show explicitly that the entropy
function approach does not work for obtaining the Bekenstein-Hawking entropy of
extremal black holes.Comment: 18 pages, v2:some points on Lifshitz black holes claified, v3:
version to appear in EJP
Thermodynamics of Gauss-Bonnet black holes revisited
We investigate the Gauss-Bonnet black hole in five dimensional anti-de Sitter
spacetimes (GBAdS). We analyze all thermodynamic quantities of the GBAdS, which
is characterized by the Gauss-Bonnet coupling and mass , comparing with
those of the Born-Infeld-AdS (BIAdS), Reissner-Norstr\"om-AdS black holes
(RNAdS), Schwarzschild-AdS (SAdS), and BTZ black holes. For we cannot
obtain the black hole with positively definite thermodynamic quantities of
mass, temperature, and entropy because the entropy does not satisfy the
area-law. On the other hand, for , we find the BIAdS-like black hole,
showing that the coupling plays the role of pseudo-charge. Importantly, we
could not obtain the SAdS in the limits of , which means that the GBAdS
is basically different from the SAdS. In addition, we clarify the connections
between thermodynamic and dynamical stability. Finally, we also conjecture that
if a black hole is big and thus globally stable, its quasinormal modes may take
analytic expressions.Comment: 22 pages, 8 figures, version to appear in EPJ
Scattering from an AdS_3 bubble and an exact AdS_3
We investigate the close relationship between the potential and absorption
cross section for test fields in an AdS bubble(a 5D black hole) and an
exact AdS. There are two solutions in type IIB string theory: an AdS
bubble corresponds to the dilatonic solution, while an exact AdS is the
non-dilatonic solution. In order to obtain the cross section for an AdS
bubble, we introduce the \{out\}-state scattering picture with the AdS-AFS
matching procedure. For an exact AdS, one considers the \{in\}-state
scattering picture with the AdS-AdS matching. Here the non-normalizable
modes are crucially taken into account for the matching procedure. It turns out
that the cross sections for the test fields in an AdS bubble take the same
forms as those in an exact AdS. This suggests that in the dilute gas and
the low energy limits, the S-matrix for an AdS bubble can be derived from
an exact AdS space.Comment: revised version to appear in Physical Review D, 26 pages with
embedded 5 EPS figures in RevTex forma
Glassy Phase Transition and Stability in Black Holes
Black hole thermodynamics, confined to the semi-classical regime, cannot
address the thermodynamic stability of a black hole in flat space. Here we show
that inclusion of correction beyond the semi-classical approximation makes a
black hole thermodynamically stable. This stability is reached through a phase
transition. By using Ehrenfest's scheme we further prove that this is a glassy
phase transition with a Prigogine-Defay ratio close to 3. This value is well
placed within the desired bound (2 to 5) for a glassy phase transition. Thus
our analysis indicates a very close connection between the phase transition
phenomena of a black hole and glass forming systems. Finally, we discuss the
robustness of our results by considering different normalisations for the
correction term.Comment: v3, minor changes over v2, references added, LaTeX-2e, 18 pages, 3 ps
figures, to appear in Eour. Phys. Jour.
Rotating Black Branes in the presence of nonlinear electromagnetic field
In this paper, we consider a class of gravity whose action represents itself
as a sum of the usual Einstein-Hilbert action with cosmological constant and an
gauge field for which the action is given by a power of the Maxwell
invariant. We present a class of the rotating black branes with Ricci flat
horizon and show that the presented solutions may be interpreted as black brane
solutions with two event horizons, extreme black hole and naked singularity
provided the parameters of the solutions are chosen suitably. We investigate
the properties of the solutions and find that for the special values of the
nonlinear parameter, the solutions are not asymptotically anti-deSitter. At
last, we obtain the conserved quantities of the rotating black branes and find
that the nonlinear source effects on the electric field, the behavior of
spacetime, type of singularity and other quantities.Comment: 7 pages, 5 figures, to appear in EPJ
dS-Holographic C-Functions with a Topological, Dilatonic Twist
Recently, the holographic aspects of asymptotically de Sitter spacetimes have
generated substantial literary interest. The plot continues in this paper, as
we investigate a certain class of dilatonically deformed ``topological'' de
Sitter solutions (which were introduced in hep-th/0110234). Although such
solutions possess a detrimental cosmological singularity, their interpretation
from a holographic perspective remains somewhat unclear. The current focus is
on the associated generalized -functions, which are shown to maintain their
usual monotonicity properties in spite of this exotic framework. These findings
suggest that such topological solutions may still play a role in our
understanding of quantum gravity with a positive cosmological constant.Comment: Latex, 30 pages; reference added and minor changes to tex
Thermodynamics of higher dimensional topological charged AdS black branes in dilaton gravity
In this paper, we study topological AdS black branes of -dimensional
Einstein-Maxwell-dilaton theory and investigate their properties. We use the
area law, surface gravity and Gauss law interpretations to find entropy,
temperature and electrical charge, respectively. We also employ the modified
Brown and York subtraction method to calculate the quasilocal mass of the
solutions. We obtain a Smarr-type formula for the mass as a function of the
entropy and the charge, compute the temperature and the electric potential
through the Smarr-type formula and show that these thermodynamic quantities
coincide with their values which are calculated through using the geometry.
Finally, we perform a stability analysis in the canonical ensemble and
investigate the effects of the dilaton field and the size of black brane on the
thermal stability of the solutions. We find that large black branes are stable
but for small black brane, depending on the value of dilaton field and type of
horizon, we encounter with some unstable phases.Comment: 21 pages, 21 figures, references updated, minor editing, accepted in
EPJC (DOI: 10.1140/epjc/s10052-010-1483-3
Challenges and Obstacles for a Bouncing Universe in Brane Models
A Brane evolving in the background of a charged AdS black-hole displays in
general a bouncing behaviour with a smooth transition from a contracting to an
expanding phase. We examine in detail the conditions and consequences of this
behaviour in various cases. For a cosmological-constant-dominated Brane, we
obtain a singularity-free, inflationary era which is shown to be compatible
only with an intermediate-scale fundamental Planck mass. For a
radiation-dominated Brane, the bouncing behaviour can occur only for
background-charge values exceeding those allowed for non-extremal black holes.
For a matter-dominated Brane, the black-hole mass affects the proper volume or
the expansion rate of the Brane. We also consider the Brane evolving in an
asymmetric background of two distinct charged AdS black hole spacetimes being
bounded by the Brane and find that, in the case of an empty critical Brane,
bouncing behaviour occurs only if the black-hole mass difference is smaller
than a certain value. The effects of a Brane curvature term on the bounce at
early and late times are also investigated.Comment: 23 pages, Latex file, comments and references added, version to
appear in Phys. Rev.