171 research outputs found
Electromagnetic Field in Higher-Dimensional Black-Hole Spacetimes
A special test electromagnetic field in the spacetime of the
higher-dimensional generally rotating NUT-(A)dS black hole is found. It is
adjusted to the hidden symmetries of the background represented by the
principal Killing-Yano tensor. Such electromagnetic field generalizes the field
of charged black hole in four dimensions. In higher dimensions, however, the
gravitational back reaction of such a field cannot be consistently solved.Comment: 8 pages, no figures; presented at the Black hole VI conference in
White Point, Canada, May 12-16 2007, and at the GRG18 conference in Sydney,
Australia, July 8-13 200
Linear stability of Einstein-Gauss-Bonnet static spacetimes. Part II: vector and scalar perturbations
We study the stability under linear perturbations of a class of static
solutions of Einstein-Gauss-Bonnet gravity in dimensions with spatial
slices of the form \Sigma_{\k}^n \times {\mathbb R}^+, \Sigma_{\k}^n an
manifold of constant curvature \k. Linear perturbations for this class of
space-times can be generally classified into tensor, vector and scalar types.
In a previous paper, tensor perturbations were analyzed. In this paper we study
vector and scalar perturbations. We show that vector perturbations can be
analyzed in general using an S-deformation approach and do not introduce
instabilities. On the other hand, we show by analyzing an explicit example
that, contrary to what happens in Einstein gravity, scalar perturbations may
lead to instabilities in black holes with spherical horizons when the
Gauss-Bonnet string corrections are taken into account.Comment: 16 pages, 6 figure
Critical escape velocity of black holes from branes
In recent work we have shown that a black hole stacked on a brane escapes
once it acquires a recoil velocity. This result was obtained in the {\it
probe-brane} approximation, {\it i.e.}, when the tension of the brane is
negligibly small. Therefore, it is not clear whether the effect of the brane
tension may prevent the black hole from escaping for small recoil velocities.
The question is whether a critical escape velocity exists. Here, we analyze
this problem by studying the interaction between a Dirac-Nambu-Goto brane and a
black hole assuming adiabatic (quasi-static) evolution. By describing the brane
in a fixed black hole spacetime, which restricts our conclusions to lowest
order effects in the tension, we find that the critical escape velocity does
not exist for co-dimension one branes, while it does for higher co-dimension
branes.Comment: 10 pages, revte
D=5 Einstein-Maxwell-Chern-Simons Black Holes
5-dimensional Einstein-Maxwell-Chern-Simons theory with Chern-Simons
coefficient has supersymmetric black holes with vanishing horizon
angular velocity, but finite angular momentum. Here supersymmetry is associated
with a borderline between stability and instability, since for a
rotational instability arises, where counterrotating black holes appear, whose
horizon rotates in the opposite sense to the angular momentum. For
black holes are no longer uniquely characterized by their global charges, and
rotating black holes with vanishing angular momentum appear.Comment: 4 pages, 4 figures, RevTeX styl
Merger Transitions in Brane--Black-Hole Systems: Criticality, Scaling, and Self-Similarity
We propose a toy model for study merger transitions in a curved spaceime with
an arbitrary number of dimensions. This model includes a bulk N-dimensional
static spherically symmetric black hole and a test D-dimensional brane
interacting with the black hole. The brane is asymptotically flat and allows
O(D-1) group of symmetry. Such a brane--black-hole (BBH) system has two
different phases. The first one is formed by solutions describing a brane
crossing the horizon of the bulk black hole. In this case the internal induced
geometry of the brane describes D-dimensional black hole. The other phase
consists of solutions for branes which do not intersect the horizon and the
induced geometry does not have a horizon. We study a critical solution at the
threshold of the brane-black-hole formation, and the solutions which are close
to it. In particular, we demonstrate, that there exists a striking similarity
of the merger transition, during which the phase of the BBH-system is changed,
both with the Choptuik critical collapse and with the merger transitions in the
higher dimensional caged black-hole--black-string system.Comment: 9 pages 2 figures; additional remarks and references are added at
Section IX "Discussion
Remark on the effective potential of the gravitational perturbation in the black hole background projected on the brane
The polar perturbation is examined when the spacetime is expressed by a 4d
metric induced from higher-dimensional Schwarzschild geometry. Since the
spacetime background is not a vacuum solution of 4d Einstein equation, the
various general principles are used to understand the behavior of the
energy-momentum tensor under the perturbation. It is found that although the
general principles fix many components, they cannot fix two components of the
energy-momentum tensor. Choosing two components suitably, we derive the
effective potential which has a correct 4d limit.Comment: 12 pages, no figure, CQG accepte
Black strings in (4+1)-dimensional Einstein-Yang-Mills theory
We study two classes of static uniform black string solutions in a
(4+1)-dimensional SU(2) Einstein-Yang-Mills model. These configurations possess
a regular event horizon and corresponds in a 4-dimensional picture to axially
symmetric black hole solutions in an Einstein-Yang-Mills-Higgs-U(1)-dilaton
theory. In this approach, one set of solutions possesses a nonzero magnetic
charge, while the other solutions represent black holes located in between a
monopole-antimonopole pair. A detailed analysis of the solutions' properties is
presented, the domain of existence of the black strings being determined. New
four dimensional solutions are found by boosting the five dimensional
configurations. We also present an argument for the non-existence of finite
mass hyperspherically symmetric black holes in SU(2) Einstein-Yang-Mills
theory.Comment: 19 Revtex pages, 27 eps-figures; discussion on rotating black holes
modifie
A Slowly Rotating Charged Black Hole in Five Dimensions
Black hole solutions in higher dimensional Einstein and Einstein-Maxwell
gravity have been discussed by Tangherlini as well as Myers and Perry a long
time ago. These solutions are the generalizations of the familiar
Schwarzschild, Reissner-Nordstrom and Kerr solutions of four-dimensional
general relativity. However, higher dimensional generalization of the
Kerr-Newman solution in four dimensions has not been found yet. As a first step
in this direction I shall report on a new solution of the Einstein-Maxwell
system of equations that describes an electrically charged and slowly rotating
black hole in five dimensions.Comment: Talk given at GR17: 17th International Conference on General
Relativity and Gravitation, Dublin, 18-24 Jule,2004 ; Corrected typos, minor
changes, new formula adde
Rotating Black Holes in Higher Dimensional Brane Worlds
A black string generaliztion of the Myers-Perry N dimensional rotating black
hole is considered in an (N+1) dimensional Randall-Sundrum brane world. The
black string intercepts the (N-1) brane in a N dimensional rotating black hole.
We examine the diverse cases arising for various non-zero rotation components
and obtain the geodesic equations for these space-time. The asymptotics of
theresulting brane world geometries and their implications are discussed.Comment: 23 pages, latex, sections rewritten and references adde
Escape of black holes from the brane
TeV-scale gravity theories allow the possibility of producing small black
holes at energies that soon will be explored at the LHC or at the Auger
observatory. One of the expected signatures is the detection of Hawking
radiation, that might eventually terminate if the black hole, once perturbed,
leaves the brane. Here, we study how the `black hole plus brane' system evolves
once the black hole is given an initial velocity, that mimics, for instance,
the recoil due to the emission of a graviton. The results of our dynamical
analysis show that the brane bends around the black hole, suggesting that the
black hole eventually escapes into the extra dimensions once two portions of
the brane come in contact and reconnect. This gives a dynamical mechanism for
the creation of baby branes.Comment: 4 pages, 6 figure
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