1,102 research outputs found

### Energy distribution of the Einstein-Klein-Gordon system for a static spherically symmetric spacetime in (2+1)-dimensions

We use Moeller's energy-momentum complex in order to explicitly compute the
energy and momentum density distributions for an exact solution of Einstein's
field equations with a negative cosmological constant minimally coupled to a
static massless scalar field in a static, spherically symmetric background in
(2+1)-dimensions.Comment: 9 pages, 1 figur

### Gravity from Local Lorentz Violation

In general relativity, gravitational waves propagate at the speed of light,
and so gravitons are massless. The masslessness can be traced to symmetry under
diffeomorphisms. However, another elegant possibility exists: masslessness can
instead arise from spontaneous violation of local Lorentz invariance. We
construct the corresponding theory of gravity. It reproduces the
Einstein-Hilbert action of general relativity at low energies and temperatures.
Detectable signals occur for sensitive experiments, and potentially profound
implications emerge for our theoretical understanding of gravity.Comment: 6 pages, accepted in General Relativity and Gravitatio

### Charged black holes in compactified spacetimes

We construct and investigate a compactified version of the four-dimensional
Reissner-Nordstrom-NUT solution, generalizing the compactified Schwarzschild
black hole that has been previously studied by several workers. Our approach to
compactification is based on dimensional reduction with respect to the
stationary Killing vector, resulting in three-dimensional gravity coupled to a
nonlinear sigma model. Using that the original non-compactified solution
corresponds to a target space geodesic, the problem can be linearized much in
the same way as in the case of no electric nor NUT charge. An interesting
feature of the solution family is that for nonzero electric charge but
vanishing NUT charge, the solution has a curvature singularity on a torus that
surrounds the event horizon, but this singularity is removed when the NUT
charge is switched on. We also treat the Schwarzschild case in a more complete
way than has been done previously. In particular, the asymptotic solution (the
Levi-Civita solution with the height coordinate made periodic) has to our
knowledge only been calculated up to a determination of the mass parameter. The
periodic Levi-Civita solution contains three essential parameters, however, and
the remaining two are explicitly calculated here.Comment: 20 pages, 3 figures. v2: Typo corrected, reference adde

### Weyl Card Diagrams and New S-brane Solutions of Gravity

We construct a new card diagram which accurately draws Weyl spacetimes and
represents their global spacetime structure, singularities, horizons and null
infinity. As examples we systematically discuss properties of a variety of
solutions including black holes as well as recent and new time-dependent
gravity solutions which fall under the S-brane class. The new time-dependent
Weyl solutions include S-dihole universes, infinite arrays and complexified
multi-rod solutions. Among the interesting features of these new solutions is
that they have near horizon scaling limits and describe the decay of unstable
objects.Comment: 78 pages, 32 figures. v2 added referenc

### Shock waves and Birkhoff's theorem in Lovelock gravity

Spherically symmetric shock waves are shown to exist in Lovelock gravity.
They amount to a change of branch of the spherically symmetric solutions across
a null hypersurface. The implications of their existence for the status of
Birkhoff's theorem in the theory is discussed.Comment: 9 pages, no figures, clarifying changes made in the text of section
III and references adde

### Weyl-type Fields with Geodesic Lines of Force

The static electrogravitational equations are studied and it is shown that an
aligned type D metric which has a Weyl-type relationship between the
gravitational and electric potential has shearfree geodesic lines of force. All
such fields are then found and turn out to be the fields of a charged sphere,
charged infinite rod and charged infinite plate. A further solution is also
found with shearing geodesic lines of force. This new solution can have $m>|e|$
or $m<|e|$, but cannot be in the Majumdar-Papapetrou class (in which $m =
|e|$). It is algebraically general and has flat equipotential surfaces.Comment: 13 pages, RevTe

### The double-Reissner-Nordstrom solution and the interaction force between two spherically symmetric charged particles

The physical representation of the general double-Reissner-Nordstrom solution
is obtained by rewriting the N=2 Breton-Manko-Aguilar electrostatic solution in
the Varzugin-Chistyakov parametrization (M_i, Q_i, R). A concise analytical
formula is derived for the interaction force between two arbitrary
Reissner-Nordstrom constituents, and an example of the equilibrium
configuration involving two oppositely charged particles which confirms earlier
Bonnor's prediction of the existence of such configurations is given.Comment: 14 pages, 1 figure; submitted to Physical Review

### Equivalence of Darmois-Israel and Distributional-Methods for Thin Shells in General Relativity

A distributional method to solve the Einstein's field equations for thin
shells is formulated. The familiar field equations and jump conditions of
Darmois-Israel formalism are derived. A carefull analysis of the Bianchi
identities shows that, for cases under consideration, they make sense as
distributions and lead to jump conditions of Darmois-Israel formalism.Comment: 17 pages Latex, no figures, to be published in Journ. Math. Phy

### Bosonic string - Kaluza Klein theory exact solutions using 5D-6D dualities

We present the explicit formulae which allow to transform the general
solution of the 6D Kaluza--Klein theory on a 3--torus into the special solution
of the 6D bosonic string theory on a 3--torus as well as into the general
solution of the 5D bosonic string theory on a 2--torus. We construct a new
family of the extremal solutions of the 3D chiral equation for the
SL(4,R)/SO(4) coset matrix and interpret it in terms of the component fields of
these three duality related theories.Comment: 13 pages in LaTe

### Purely electromagnetic spacetimes

Electrovacuum solutions devoid of usual mass sources are classified in the
case of one, two and three commuting Killing vectors. Three branches of
solutions exist. Electromagnetically induced mass terms appear in some of them.Comment: 8 page

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