1,173 research outputs found
Multi-black rings and the phase diagram of higher-dimensional black holes
Configurations of multiple concentric black rings play an important role in
determining the pattern of branchings, connections and mergers between
different phases of higher-dimensional black holes. We examine them using both
approximate and (in five dimensions) exact methods. By identifying the role of
the different scales in the system, we argue that it is possible to have
multiple black ring configurations in which all the rings have equal
temperature and angular velocity. This allows us to correct and improve in a
simple, natural manner, an earlier proposal for the phase diagram of
singly-rotating black holes in .Comment: 14 pages, 2 figure
Braneworlds and Dark Energy
In the Randall-Sundrum scenario, we analyse the dynamics of an AdS5
braneworld when conformal matter fields propagate in five dimensions. We show
that conformal fields of weight -4 are associated with stable geometries which
describe the dynamics of inhomogeneous dust, generalized dark radiation and
homogeneous polytropic dark energy on a spherically symmetric 3-brane embedded
in the compact AdS5 orbifold. We discuss aspects of the radion stability
conditions and of the localization of gravity in the vicinity of the brane.Comment: 12 pages, latex, 3 eps figures. Talk given at the Seventh Workshop on
Quantum Field Theory under the Influence of External Conditions, IEEC, CSIC
and University of Barcelona, Barcelona, Catalonia, Spain, 5-9 September 2005.
Revised version published in the workshop proceedings, J. Phys. A:
Mathematical and General. Typos corrected and some changes introduced for
clarit
Cutoff AdS/CFT duality and the quest for braneworld black holes
We present significant evidence in favour of the holographic conjecture that
``4D black holes localized on the brane found by solving the classical bulk
equations in are quantum corrected black holes and not classical
ones''. The crucial test is the calculation of the quantum correction to the
Newtonian potential based on a numerical computation of in
Schwarzschild spacetime for matter fields in the zero temperature Boulware
vacuum state. For the case of the conformally invariant scalar field the
leading order term is found to be $M/45\pi r^3$. This result is equivalent to
the result which was previously obtained in the weak-field approximation using
Feynman diagrams and which has been shown to be equivalent, via the AdS/CFT
duality, to the analogous calculation in Randall-Sundrum braneworlds. This
asymptotic behavior was not captured in the analytical approximations for
proposed in the literature. The 4D backreaction equations are then
used to make a prediction about the existence and the possible spacetime
structure of macroscopic static braneworld black holes.Comment: 4 pages, 2 figure
Derivation of the blackfold effective theory
We study fluctuations and deformations of black branes over length scales
larger than the horizon radius. We prove that the Einstein equations for the
perturbed p-brane yield, as constraints, the equations of the effective
blackfold theory. We solve the Einstein equations for the perturbed geometry
and show that it remains regular on and outside the black brane horizon. This
study provides an ab initio derivation of the blackfold effective theory and
gives explicit expressions for the metrics near the new black holes and black
branes that result from it, to leading order in a derivative expansion.Comment: 20 pages. v4: Typo corrected in eq. (6.11) -- erratum in the
published versio
Blackfolds in (Anti)-de Sitter Backgrounds
We construct different neutral blackfold solutions in Anti-de Sitter and de
Sitter background spacetimes in the limit where the cosmological scale is taken
to be much larger than the transverse horizon size. This includes a class of
blackfolds with horizons that are products of odd-spheres times a transverse
sphere, for which the thermodynamic stability is also studied. Moreover, we
exhibit a specific case in which the same blackfold solution can describe
different limiting black hole spacetimes therefore illustrating the geometric
character of the blackfold approach. Furthermore, we show that the
higher-dimensional Kerr-(Anti)-de Sitter black hole allows for ultra-spinning
regimes in the relevant limit of large cosmological scale, and demonstrate that
this is correctly described by a pancaked blackfold geometry. We also give
evidence for the possibility of saturating the rigidity theorem in these
backgrounds.Comment: v1: 1+29 pages, latex. v2: cosmetic changes. v3: .pdf file correcte
Exact Microscopic Entropy of Non-Supersymmetric Extremal Black Rings
In this brief note we show that the horizon entropy of the largest known
class of non-supersymmetric extremal black rings, with up to six parameters, is
exactly reproduced for all values of the ring radius using the same conformal
field theory of the four-charge four-dimensional black hole. A particularly
simple case is a dipole black ring without any conserved charges. The mass gets
renormalized, but the first corrections it receives can be easily understood as
an interaction potential energy. Finally, we stress that even if the entropy is
correctly reproduced, this only implies that one sector of chiral excitations
has been identified, but an understanding of excitations in the other sector is
still required in order to capture the black ring dynamics.Comment: 7 pages. v2: minor improvements, ref adde
Dynamics and Stability of Black Rings
We examine the dynamics of neutral black rings, and identify and analyze a
selection of possible instabilities. We find the dominating forces of very thin
black rings to be a Newtonian competition between a string-like tension and a
centrifugal force. We study in detail the radial balance of forces in black
rings, and find evidence that all fat black rings are unstable to radial
perturbations, while thin black rings are radially stable. Most thin black
rings, if not all of them, also likely suffer from Gregory-Laflamme
instabilities. We also study simple models for stability against
emission/absorption of massless particles. Our results point to the conclusion
that most neutral black rings suffer from classical dynamical instabilities,
but there may still exist a small range of parameters where thin black rings
are stable. We also discuss the absence of regular real Euclidean sections of
black rings, and thermodynamics in the grand-canonical ensemble.Comment: 39 pages, 17 figures; v2: conclusions concerning radial stability
corrected + new appendix + refs added; v3: additional comments regarding
stabilit
A Charged Doubly Spinning Black Ring
This paper calculates the general form of a 5d metric when fundamental string
and momentum charges are added. This is accomplished using the standard method
of boosting and T-dualising a solution to Einstein's equations, where the
solution has three Killing vectors and is expressed in a generic form. The
thermodynamical properties of the charged solution are derived and the physical
implications of the solution are then examined with the two-charge dual
spinning black ring being used as an example.Comment: 22 pages, 4 figure
Simple solutions to the Einstein Equations in spaces with unusual topology
We discuss simple vacuum solutions to the Einstein Equations in five
dimensional space-times compactified in two different ways. In such spaces, one
black hole phase and more then one black string phase may exist. Several old
metrics are adapted to new background topologies to yield new solutions to the
Einstein Equations. We then briefly talk about the angular momentum they may
carry, the horizon topology and phase transitions that may occur.Comment: Published versions. Includes referee input. 10 pages, 3 figure
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