14,395 research outputs found
First Law of Black Rings Thermodynamics in Higher Dimensional Dilaton Gravity with p + 1 Strength Forms
We derive the first law of black rings thermodynamics in n-dimensional
Einstein dilaton gravity with additional (p+1)-form field strength being the
simplest generalization of five-dimensional theory containing a stationary
black ring solution with dipole charge. It was done by means of choosing any
cross section of the event horizon to the future of the bifurcation surface.Comment: 6 pages, to be published in Phys.Rev.D1
Non-Abelian pp-waves in D=4 supergravity theories
The non-Abelian plane waves, first found in flat spacetime by Coleman and
subsequently generalized to give pp-waves in Einstein-Yang-Mills theory, are
shown to be 1/2 supersymmetric solutions of a wide variety of N=1 supergravity
theories coupled to scalar and vector multiplets, including the theory of SU(2)
Yang-Mills coupled to an axion \sigma and dilaton \phi recently obtained as the
reduction to four-dimensions of the six-dimensional Salam-Sezgin model. In this
latter case they provide the most general supersymmetric solution. Passing to
the Riemannian formulation of this theory we show that the most general
supersymmetric solution may be constructed starting from a self-dual Yang-Mills
connection on a self-dual metric and solving a Poisson equation for e^\phi. We
also present the generalization of these solutions to non-Abelian AdS pp-waves
which allow a negative cosmological constant and preserve 1/4 of supersymmetry.Comment: Latex, 1+12 page
Time-Dependent Multi-Centre Solutions from New Metrics with Holonomy Sim(n-2)
The classifications of holonomy groups in Lorentzian and in Euclidean
signature are quite different. A group of interest in Lorentzian signature in n
dimensions is the maximal proper subgroup of the Lorentz group, SIM(n-2).
Ricci-flat metrics with SIM(2) holonomy were constructed by Kerr and Goldberg,
and a single four-dimensional example with a non-zero cosmological constant was
exhibited by Ghanam and Thompson. Here we reduce the problem of finding the
general -dimensional Einstein metric of SIM(n-2) holonomy, with and without
a cosmological constant, to solving a set linear generalised Laplace and
Poisson equations on an (n-2)-dimensional Einstein base manifold. Explicit
examples may be constructed in terms of generalised harmonic functions. A
dimensional reduction of these multi-centre solutions gives new time-dependent
Kaluza-Klein black holes and monopoles, including time-dependent black holes in
a cosmological background whose spatial sections have non-vanishing curvature.Comment: Typos corrected; 29 page
Moduli, Scalar Charges, and the First Law of Black Hole Thermodynamics
We show that under variation of moduli fields the first law of black
hole thermodynamics becomes , where are the scalar charges. We also show
that the ADM mass is extremized at fixed , , when the moduli
fields take the fixed value which depend only on electric
and magnetic charges. It follows that the least mass of any black hole with
fixed conserved electric and magnetic charges is given by the mass of the
double-extreme black hole with these charges. Our work allows us to interpret
the previously established result that for all extreme black holes the moduli
fields at the horizon take a value depending only
on the electric and magnetic conserved charges: is such
that the scalar charges .Comment: 3 pages, no figures, more detailed versio
Multi-black holes and instantons in effective string theory
The effective action for string theory which takes into account non-minimal
coupling of moduli admits multi-black hole solutions. The euclidean
continuation of these solutions can be interpreted as an instanton mediating
the splitting and recombination of the throat of extremal magnetically charged
black holes.Comment: 10 pages, plain Te
First Law of Black Saturn Thermodynamics
The physical version and equilibrium state version of the first law of
thermodynamics for a black object consisting of n-dimensional charged
stationary axisymmetric black hole surrounded by black rings, the so-called
black Saturn was derived. The general setting for our derivation is
n-dimensional dilaton gravity with p + 1 strength form fields.Comment: 9 pages, RevTex, to be published in Phys.Rev.D1
On the Obstructions to non-Cliffordian Pin Structures
We derive the topological obstructions to the existence of non-Cliffordian
pin structures on four-dimensional spacetimes. We apply these obstructions to
the study of non-Cliffordian pin-Lorentz cobordism. We note that our method of
derivation applies equally well in any dimension and in any signature, and we
present a general format for calculating obstructions in these situations.
Finally, we interpret the breakdown of pin structure and discuss the relevance
of this to aspects of physics.Comment: 31 pages, latex, published in Comm. Math. Phys. 164, No. 1, pages
65-87 (1994
The Cardy-Verlinde formula and entropy of Topological Reissner-Nordstr\"om black holes in de Sitter spaces
In this paper we discuss the question of whether the entropy of cosmological
horizon in Topological Reissner-Nordstr\"om- de Sitter spaces can be described
by the Cardy-Verlinde formula, which is supposed to be an entropy formula of
conformal field theory in any dimension. Furthermore, we find that the entropy
of black hole horizon can also be rewritten in terms of the Cardy-Verlinde
formula for these black holes in de Sitter spaces, if we use the definition due
to Abbott and Deser for conserved charges in asymptotically de Sitter spaces.
Our result is in favour of the dS/CFT correspondence.Comment: 6 pages, accepted for publication in IJMP
Non-asymptotically flat, non-AdS dilaton black holes
We show that previously known non-asymptotically flat static black hole
solutions of Einstein-Maxwell-dilaton theory may be obtained as near-horizon
limits of asymptotically flat black holes. Specializing to the case of the
dilaton coupling constant , we generate from the
non-asymptotically flat magnetostatic or electrostatic black holes two classes
of rotating dyonic black hole solutions. The rotating dyonic black holes of the
``magnetic'' class are dimensional reductions of the five-dimensional
Myers-Perry black holes relative to one of the azimuthal angles, while those of
the ``electric'' class are twisted dimensional reductions of rotating dyonic
Rasheed black strings. We compute the quasi-local mass and angular momentum of
our rotating dyonic black holes, and show that they satisfy the first law of
black hole thermodynamics, as well as a generalized Smarr formula. We also
discuss the construction of non-asymptotically flat multi-extreme black hole
configurations.Comment: Minor corrections. 2 references added. To appear in Physical Review
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