10 research outputs found
Uniqueness of (dilatonic) charged black holes and black p-branes in higher dimensions
We prove the uniqueness of higher dimensional (dilatonic) charged black holes
in static and asymptotically flat spacetimes for arbitrary vector-dilaton
coupling constant. An application to the uniqueness of a wide class of black
p-branes is also given.Comment: 6 page
Uniqueness Theorem for Generalized Maxwell Electric and Magnetic Black Holes in Higher Dimensions
Based on the conformal energy theorem we prove the uniqueness theorem for
static higher dimensional electrically and magnetically charged black holes
being the solution of Einstein (n-2)-gauge forms equations of motion. Black
hole spacetime contains an asymptotically flat spacelike hypersurface with
compact interior and non-degenerate components of the event horizon.Comment: 7 pages, RevTex, to be published in Phys.Rev.D1
Static perfect fluids with Pant-Sah equations of state
We analyze the 3-parameter family of exact, regular, static, spherically
symmetric perfect fluid solutions of Einstein's equations (corresponding to a
2-parameter family of equations of state) due to Pant and Sah and
"rediscovered" by Rosquist and the present author. Except for the Buchdahl
solutions which are contained as a limiting case, the fluids have finite radius
and are physically realistic for suitable parameter ranges. The equations of
state can be characterized geometrically by the property that the 3-metric on
the static slices, rescaled conformally with the fourth power of any linear
function of the norm of the static Killing vector, has constant scalar
curvature. This local property does not require spherical symmetry; in fact it
simplifies the the proof of spherical symmetry of asymptotically flat solutions
which we recall here for the Pant-Sah equations of state. We also consider a
model in Newtonian theory with analogous geometric and physical properties,
together with a proof of spherical symmetry of the asymptotically flat
solutions.Comment: 32 p., Latex, minor changes and correction
TIME-SYMMETRIC INITIAL DATA SETS IN 4--D DILATON GRAVITY
I study the time--symmetric initial--data problem in theories with a massless
scalar field (dilaton), free or coupled to a Maxwell field in the stringy way,
finding different initial--data sets describing an arbitrary number of black
holes with arbitrary masses, charges and asymptotic value of the dilaton. The
presence of the scalar field gives rise to a number of interesting effects. The
mass and charges of a single black hole are different in its two asymptotically
flat regions across the Einstein--Rosen bridge. The same happens to the value
of the dilaton at infinity. This forbids the identification of these asymptotic
regions in order to build (Misner) wormholes in the most naive way. Using
different techniques, I find regular initial data for stringy wormholes. The
price payed is the existence singularities in the dilaton field. The presence
of a single--valued scalar seems to constrain strongly the allowed topologies
of the initial space--like surface. Other kinds of scalar fields (taking values
on a circle or being defined up to an additive constant) are also briefly
considered.Comment: latex file, 38 pages
Topological and geometrical restrictions, free-boundary problems and self-gravitating fluids
Let (P1) be certain elliptic free-boundary problem on a Riemannian manifold
(M,g). In this paper we study the restrictions on the topology and geometry of
the fibres (the level sets) of the solutions f to (P1). We give a technique
based on certain remarkable property of the fibres (the analytic representation
property) for going from the initial PDE to a global analytical
characterization of the fibres (the equilibrium partition condition). We study
this analytical characterization and obtain several topological and geometrical
properties that the fibres of the solutions must possess, depending on the
topology of M and the metric tensor g. We apply these results to the classical
problem in physics of classifying the equilibrium shapes of both Newtonian and
relativistic static self-gravitating fluids. We also suggest a relationship
with the isometries of a Riemannian manifold.Comment: 36 pages. In this new version the analytic representation hypothesis
is proved. Please address all correspondence to D. Peralta-Sala
Time-Independent Gravitational Fields
This article reviews, from a global point of view, rigorous results on time
independent spacetimes. Throughout attention is confined to isolated bodies at
rest or in uniform rotation in an otherwise empty universe. The discussion
starts from first principles and is, as much as possible, self-contained.Comment: 47 pages, LaTeX, uses Springer cl2emult styl
Non-existence theorems for Yang-Mills fields outside the black hole of the Schwarzschild spacetime
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