233 research outputs found
Supergravity p-branes revisited: extra parameters, uniqueness, and topological censorship
We perform a complete integration of the Einstein-dilaton-antisymmetric form
action describing black p-branes in arbitrary dimensions assuming the
transverse space to be homogeneous and possessing spherical, toroidal or
hyperbolic topology. The generic solution contains eight parameters satisfying
one constraint. Asymptotically flat solutions form a five-parametric subspace,
while conditions of regularity of the non-degenerate event horizon further
restrict this number to three, which can be related to the mass and the charge
densities and the asymptotic value of the dilaton. In the case of a degenerate
horizon, this number is reduced by one. Our derivation constitutes a
constructive proof of the uniqueness theorem for -branes with the
homogeneous transverse space. No asymptotically flat solutions with toroidal or
hyperbolic transverse space within the considered class are shown to exist,
which result can be viewed as a demonstration of the topological censorship for
p-branes. From our considerations it follows, in particular, that some
previously discussed p-brane-like solutions with extra parameters do not
satisfy the standard conditions of asymptotic flatness and absence of naked
singularities. We also explore the same system in presence of a cosmological
constant, and derive a complete analytic solution for higher-dimensional
charged topological black holes, thus proving their uniqueness.Comment: Revtex4, no figure
Static black holes with a negative cosmological constant: Deformed horizon and anti-de Sitter boundaries
Using perturbative techniques, we investigate the existence and properties of
a new static solution for the Einstein equation with a negative cosmological
constant, which we call the deformed black hole. We derive a solution for a
static and axisymmetric perturbation of the Schwarzschild-anti-de Sitter black
hole that is regular in the range from the horizon to spacelike infinity. The
key result is that this perturbation simultaneously deforms the two boundary
surfaces--i.e., both the horizon and spacelike two-surface at infinity. Then we
discuss the Abbott-Deser mass and the Ashtekar-Magnon one for the deformed
black hole, and according to the Ashtekar-Magnon definition, we construct the
thermodynamic first law of the deformed black hole. The first law has a
correction term which can be interpreted as the work term that is necessary for
the deformation of the boundary surfaces. Because the work term is negative,
the horizon area of the deformed black hole becomes larger than that of the
Schwarzschild-anti-de Sitter black hole, if compared under the same mass,
indicating that the quasistatic deformation of the Schwarzschild-anti-de Sitter
black hole may be compatible with the thermodynamic second law (i.e., the area
theorem).Comment: 31 pages, 5 figures, one reference added, to be published in PR
Nariai, Bertotti-Robinson and anti-Nariai solutions in higher dimensions
We find all the higher dimensional solutions of the Einstein-Maxwell theory
that are the topological product of two manifolds of constant curvature. These
solutions include the higher dimensional Nariai, Bertotti-Robinson and
anti-Nariai solutions, and the anti-de Sitter Bertotti-Robinson solutions with
toroidal and hyperbolic topology (Plebanski-Hacyan solutions). We give explicit
results for any dimension D>3. These solutions are generated from the
appropriate extremal limits of the higher dimensional near-extreme black holes
in a de Sitter, and anti-de Sitter backgrounds. Thus, we also find the mass and
the charge parameters of the higher dimensional extreme black holes as a
function of the radius of the degenerate horizon.Comment: 10 pages, 11 figures, RevTeX4. References added. Published versio
The extremal limits of the C-metric: Nariai, Bertotti-Robinson and anti-Nariai C-metrics
In two previous papers we have analyzed the C-metric in a background with a
cosmological constant, namely the de Sitter (dS) C-metric, and the anti-de
Sitter (AdS) C-metric, following the work of Kinnersley and Walker for the flat
C-metric. These exact solutions describe a pair of accelerated black holes in
the flat or cosmological constant background, with the acceleration A being
provided by a strut in-between that pushes away the two black holes. In this
paper we analyze the extremal limits of the C-metric in a background with
generic cosmological constant. We follow a procedure first introduced by
Ginsparg and Perry in which the Nariai solution, a spacetime which is the
direct topological product of the 2-dimensional dS and a 2-sphere, is generated
from the four-dimensional dS-Schwarzschild solution by taking an appropriate
limit, where the black hole event horizon approaches the cosmological horizon.
Similarly, one can generate the Bertotti-Robinson metric from the
Reissner-Nordstrom metric by taking the limit of the Cauchy horizon going into
the event horizon of the black hole, as well as the anti-Nariai by taking an
appropriate solution and limit. Using these methods we generate the C-metric
counterparts of the Nariai, Bertotti-Robinson and anti-Nariai solutions, among
others. One expects that the solutions found in this paper are unstable and
decay into a slightly non-extreme black hole pair accelerated by a strut or by
strings. Moreover, the Euclidean version of these solutions mediate the quantum
process of black hole pair creation, that accompanies the decay of the dS and
AdS spaces
Topological Charged Black Holes in High Dimensional Spacetimes and Their Formation from Gravitational Collapse of a Type II Fluid
Topological charged black holes coupled with a cosmological constant in
spacetimes are studied, where is an Einstein
space of the form . The global structure for
the four-dimensional spacetimes with is investigated systematically.
The most general solutions that represent a Type fluid in such a high
dimensional spacetime are found, and showed that topological charged black
holes can be formed from the gravitational collapse of such a fluid. When the
spacetime is (asymptotically) self-similar, the collapse always forms black
holes for , in contrast to the case , where it can form
either balck holes or naked singularities.Comment: 14 figures, to appear in Phys. Rev.
Quasinormal modes for massless topological black holes
An exact expression for the quasinormal modes of scalar perturbations on a
massless topological black hole in four and higher dimensions is presented. The
massive scalar field is nonminimally coupled to the curvature, and the horizon
geometry is assumed to have a negative constant curvature.Comment: CECS style, 11 pages, no figures. References adde
Thermodynamic and gravitational instability on hyperbolic spaces
We study the properties of anti--de Sitter black holes with a Gauss-Bonnet
term for various horizon topologies (k=0, \pm 1) and for various dimensions,
with emphasis on the less well understood k=-1 solution. We find that the zero
temperature (and zero energy density) extremal states are the local minima of
the energy for AdS black holes with hyperbolic event horizons. The hyperbolic
AdS black hole may be stable thermodynamically if the background is defined by
an extremal solution and the extremal entropy is non-negative. We also
investigate the gravitational stability of AdS spacetimes of dimensions D>4
against linear perturbations and find that the extremal states are still the
local minima of the energy. For a spherically symmetric AdS black hole
solution, the gravitational potential is positive and bounded, with or without
the Gauss-Bonnet type corrections, while, when k=-1, a small Gauss-Bonnet
coupling, namely, \alpha << {l}^2 (where l is the curvature radius of AdS
space), is found useful to keep the potential bounded from below, as required
for stability of the extremal background.Comment: Shortened to match published (PRD) version, 18 pages, several eps
figure
Ricci flat rotating black branes with a conformally invariant Maxwell source
We consider Einstein gravity coupled to an gauge field for which the
density is given by a power of the Maxwell Lagrangian. In -dimensions the
action of Maxwell field is shown to enjoy the conformal invariance if the power
is chosen as . We present a class of charge rotating solutions in
Einstein-conformally invariant Maxwell gravity in the presence of a
cosmological constant. These solutions may be interpreted as black brane
solutions with inner and outer event horizons or an extreme black brane
depending on the value of the mass parameter. Since we are considering power of
the Maxwell density, the black brane solutions exist only for dimensions which
are multiples of four. We compute conserved and thermodynamics quantities of
the black brane solutions and show that the expression of the electric field
does not depend on the dimension. Also, we obtain a Smarr-type formula and show
that these conserved and thermodynamic quantities of black branes satisfy the
first law of thermodynamics. Finally, we study the phase behavior of the
rotating black branes and show that there is no Hawking--Page phase transition
in spite of conformally invariant Maxwell field.Comment: 13 pages, one figur
Radial asymptotics of Lemaitre-Tolman-Bondi dust models
We examine the radial asymptotic behavior of spherically symmetric
Lemaitre-Tolman-Bondi dust models by looking at their covariant scalars along
radial rays, which are spacelike geodesics parametrized by proper length
, orthogonal to the 4-velocity and to the orbits of SO(3). By introducing
quasi-local scalars defined as integral functions along the rays, we obtain a
complete and covariant representation of the models, leading to an initial
value parametrization in which all scalars can be given by scaling laws
depending on two metric scale factors and two basic initial value functions.
Considering regular "open" LTB models whose space slices allow for a diverging
, we provide the conditions on the radial coordinate so that its
asymptotic limit corresponds to the limit as . The "asymptotic
state" is then defined as this limit, together with asymptotic series expansion
around it, evaluated for all metric functions, covariant scalars (local and
quasi-local) and their fluctuations. By looking at different sets of initial
conditions, we examine and classify the asymptotic states of parabolic,
hyperbolic and open elliptic models admitting a symmetry center. We show that
in the radial direction the models can be asymptotic to any one of the
following spacetimes: FLRW dust cosmologies with zero or negative spatial
curvature, sections of Minkowski flat space (including Milne's space), sections
of the Schwarzschild--Kruskal manifold or self--similar dust solutions.Comment: 44 pages (including a long appendix), 3 figures, IOP LaTeX style.
Typos corrected and an important reference added. Accepted for publication in
General Relativity and Gravitatio
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
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