490 research outputs found
AdSS_5 Brane World Cosmology
The gravitational equations of the 5-dimensional analogue of the AdSS
space-time, where all the matter fields are confined on the 3-brane are
examined. The most general solutions are established in the generic case of a
non-Z_2-symmetric bulk. Constraining these solutions we derive a number of
remarkable metrics widely investigated in the literature. Finally, we make many
important conclusions about the viability of the presented scenario and
cosmology.Comment: JHEP file, 8 pages, v5: Corrected typo
Thermodynamics of a Kerr Newman de Sitter Black Hole
We compute the conserved quantities of the four-dimensional Kerr-Newman-dS
(KNdS) black hole through the use of the counterterm renormalization method,
and obtain a generalized Smarr formula for the mass as a function of the
entropy, the angular momentum and the electric charge. The first law of
thermodynamics associated to the cosmological horizon of KNdS is also
investigated. Using the minimal number of intrinsic boundary counterterms, we
consider the quasilocal thermodynamics of asymptotic de Sitter
Reissner-Nordstrom black hole, and find that the temperature is equal to the
product of the surface gravity (divided by ) and the Tolman redshift
factor. We also perform a quasilocal stability analysis by computing the
determinant of Hessian matrix of the energy with respect to its thermodynamic
variables in both the canonical and the grand-canonical ensembles and obtain a
complete set of phase diagrams. We then turn to the quasilocal thermodynamics
of four-dimensional Kerr-Newman-de Sitter black hole for virtually all possible
values of the mass, the rotation and the charge parameters that leave the
quasilocal boundary inside the cosmological event horizon, and perform a
quasilocal stability analysis of KNdS black hole.Comment: REVTEX4, 12 pages, 12 figures, references added and some points in
Sec II have been clarified, version to appear in Can. J. Phy
Charged AdS Black Holes and Catastrophic Holography
We compute the properties of a class of charged black holes in anti-de Sitter
space-time, in diverse dimensions. These black holes are solutions of
consistent Einstein-Maxwell truncations of gauged supergravities, which are
shown to arise from the inclusion of rotation in the transverse space. We
uncover rich thermodynamic phase structures for these systems, which display
classic critical phenomena, including structures isomorphic to the van der
Waals-Maxwell liquid-gas system. In that case, the phases are controlled by the
universal `cusp' and `swallowtail' shapes familiar from catastrophe theory. All
of the thermodynamics is consistent with field theory interpretations via
holography, where the dual field theories can sometimes be found on the world
volumes of coincident rotating branes.Comment: 19 pages, revtex, psfig, 6 multicomponent figures, typos, references
and a few remarks have been repaired, and adde
Duality of Quasilocal Gravitational Energy and Charges with Non-orthogonal Boundaries
We study the duality of quasilocal energy and charges with non-orthogonal
boundaries in the (2+1)-dimensional low-energy string theory. Quasilocal
quantities shown in the previous work and some new variables arisen from
considering the non-orthogonal boundaries as well are presented, and the boost
relations between those quantities are discussed. Moreover, we show that the
dual properties of quasilocal variables such as quasilocal energy density,
momentum densities, surface stress densities, dilaton pressure densities, and
Neuve-Schwarz(NS) charge density, are still valid in the moving observer's
frame.Comment: 19pages, 1figure, RevTe
Holographic Description of Gravitational Anomalies
The holographic duality can be extended to include quantum theories with
broken coordinate invariance leading to the appearance of the gravitational
anomalies. On the gravity side one adds the gravitational Chern-Simons term to
the bulk action which gauge invariance is only up to the boundary terms. We
analyze in detail how the gravitational anomalies originate from the modified
Einstein equations in the bulk. As a side observation we find that the
gravitational Chern-Simons functional has interesting conformal properties. It
is invariant under conformal transformations. Moreover, its metric variation
produces conformal tensor which is a generalization of the Cotton tensor to
dimension . We calculate the modification of the holographic
stress-energy tensor that is due to the Chern-Simons term and use the bulk
Einstein equations to find its divergence and thus reproduce the gravitational
anomaly. Explicit calculation of the anomaly is carried out in dimensions
and . The result of the holographic calculation is compared with that of
the descent method and agreement is found. The gravitational Chern-Simons term
originates by Kaluza-Klein mechanism from a one-loop modification of M-theory
action. This modification is discussed in the context of the gravitational
anomaly in six-dimensional theory. The agreement with earlier
conjectured anomaly is found.Comment: 24 pages, Latex; presentation re-structured, new references adde
Hawking Radiation from AdS Black Holes
We investigate Hawking radiation from black holes in (d+1)-dimensional
anti-de Sitter space. We focus on s-waves, make use of the geometrical optics
approximation, and follow three approaches to analyze the radiation. First, we
compute a Bogoliubov transformation between Kruskal and asymptotic coordinates
and compare the different vacua. Second, following a method due to Kraus,
Parikh, and Wilczek, we view Hawking radiation as a tunneling process across
the horizon and compute the tunneling probablility. This approach uses an
anti-de Sitter version of a metric originally introduced by Painleve for
Schwarzschild black holes. From the tunneling probability one also finds a
leading correction to the semi-classical emission rate arising from the
backreaction to the background geometry. Finally, we consider a spherically
symmetric collapse geometry and the Bogoliubov transformation between the
initial vacuum state and the vacuum of an asymptotic observer.Comment: 13 pages, latex2e, v2: some clarifications and references adde
Charged and rotating AdS black holes and their CFT duals
Black hole solutions that are asymptotic to or can rotate in two different ways. If the internal sphere rotates
then one can obtain a Reissner-Nordstrom-AdS black hole. If the asymptotically
AdS space rotates then one can obtain a Kerr-AdS hole. One might expect
superradiant scattering to be possible in either of these cases. Superradiant
modes reflected off the potential barrier outside the hole would be
re-amplified at the horizon, and a classical instability would result. We point
out that the existence of a Killing vector field timelike everywhere outside
the horizon prevents this from occurring for black holes with negative action.
Such black holes are also thermodynamically stable in the grand canonical
ensemble. The CFT duals of these black holes correspond to a theory in an
Einstein universe with a chemical potential and a theory in a rotating Einstein
universe. We study these CFTs in the zero coupling limit. In the first case,
Bose-Einstein condensation occurs on the boundary at a critical value of the
chemical potential. However the supergravity calculation demonstrates that this
is not to be expected at strong coupling. In the second case, we investigate
the limit in which the angular velocity of the Einstein universe approaches the
speed of light at finite temperature. This is a new limit in which to compare
the CFT at strong and weak coupling. We find that the free CFT partition
function and supergravity action have the same type of divergence but the usual
factor of 4/3 is modified at finite temperature.Comment: 18 pages, RevTex, 2 figures; v2: references adde
Brane-world creation and black holes
An inflating brane-world can be created from ``nothing'' together with its
Anti-de Sitter (AdS) bulk. The resulting space-time has compact spatial
sections bounded by the brane. During inflation, the continuum of KK modes is
separated from the massless zero mode by the gap , where is the
Hubble rate. We consider the analog of the Nariai solution and argue that it
describes pair production of ``Black cigars'' attached to the inflating brane.
In the case when the size of the instantons is much larger than the AdS radius,
the 5-dimensional action agrees with the 4-dimensional one. Hence, the 5D and
4D gravitational entropies are the same in this limit. We also consider thermal
instantons with an AdS black hole in the bulk. These may be interpreted as
describing the creation of a hot universe from nothing, or the production of
AdS black holes in the vicinity of a pre-existing inflating brane-world. The
Lorentzian evolution of the brane-world after creation is briefly discussed. An
additional "integration constant" in the Friedmann equation -accompanying a
term which dilutes like radiation- describes the tidal force in the fifth
direction and arises from the mass of a spherical object inside the bulk. This
could be a 5-dimensional black hole or a "parallel" brane-world of negative
tension concentrical with our brane-world. In the case of thermal solutions,
and in the spirit of the correspondence, one may attribute the
additional term to thermal radiation in the boundary theory. Then, for
temperatures well below the AdS scale, the entropy of this radiation agrees
with the entropy of the black hole in the AdS bulk.Comment: 15 pages, 2 figures, LaTeX. References added, typos corrected, added
Comment on AdS/CFT correspondenc
Trace anomaly driven inflation
This paper investigates Starobinsky's model of inflation driven by the trace
anomaly of conformally coupled matter fields. This model does not suffer from
the problem of contrived initial conditions that occurs in most models of
inflation driven by a scalar field. The universe can be nucleated
semi-classically by a cosmological instanton that is much larger than the
Planck scale provided there are sufficiently many matter fields. There are two
cosmological instantons: the four sphere and a new ``double bubble'' solution.
This paper considers a universe nucleated by the four sphere. The AdS/CFT
correspondence is used to calculate the correlation function for scalar and
tensor metric perturbations during the ensuing de Sitter phase. The analytic
structure of the scalar and tensor propagators is discussed in detail.
Observational constraints on the model are discussed. Quantum loops of matter
fields are shown to strongly suppress short scale metric perturbations, which
implies that short distance modifications of gravity would probably not be
observable in the cosmic microwave background. This is probably true for any
model of inflation provided there are sufficiently many matter fields. This
point is illustrated by a comparison of anomaly driven inflation in four
dimensions and in a Randall-Sundrum brane-world model.Comment: LaTeX, 42 pages, 5 .eps figures. v2: typos corrected, references
added and 2 new paragraphs in conclusions section. v3: comments about strong
coupling and unboundedness of action changed, other minor changes. v4:
Comments about strong coupling changed again (2-point functions of metric
perturbations do not depend on Yang-Mills coupling
Hawking Radiation as Tunneling through the Quantum Horizon
Planck-scale corrections to the black-hole radiation spectrum in the
Parikh-Wilczek tunneling framework are calculated. The corrective terms arise
from modifications in the expression of the surface gravity in terms of the
mass-energy of the black hole-emitted particle system. The form of the new
spectrum is discussed together with the possible consequences for the fate of
black holes in the late stages of evaporation.Comment: 13 pages; the contents of this paper overlap somewhat with the
earlier submissions hep-th/0504188 and gr-qc/0505015; (v2) references added
and various cosmetic (but no physics) changes, to appear in JHE
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