48 research outputs found
Conditions for nonexistence of static or stationary, Einstein-Maxwell, non-inheriting black-holes
We consider asymptotically-flat, static and stationary solutions of the
Einstein equations representing Einstein-Maxwell space-times in which the
Maxwell field is not constant along the Killing vector defining stationarity,
so that the symmetry of the space-time is not inherited by the electromagnetic
field. We find that static degenerate black hole solutions are not possible
and, subject to stronger assumptions, nor are static, non-degenerate or
stationary black holes. We describe the possibilities if the stronger
assumptions are relaxed.Comment: 19 pages, to appear in GER
Zur Klassifizierung mehrparametriger Dämpfungsmodelle
Vier Dämpfungsmodelle wurden in Nolte und Müller zum Hagen (2005) hinsichtlich ihrer mathematischen Struktur beschriebenen: Das Maxwell-Modell, das Jeffreys-Modell, das Kelvin-Voigt-Modell sowie das Poynting-Thomson-Modell. Die Diskussion der Modelle erfolgte an den partiellen Differentialgleichungen in der Verschiebung. Weitere physikalische Untersuchungen fanden statt. Es hat sich, dass zwei der partiellen Differentialgleichungen (Dämpfungsmodell nach Maxwell und Poynting-Thomson) rein hyperbolisch sind und die zwei anderen partiellen Differentialgleichungen vom parabolischen-hyperbolischen Typ sind. Diese Erkenntnis wird in dieser Arbeit auf mehrparametrige Dämpfungsmodelle übertragen
Einstein equations in the null quasi-spherical gauge III: numerical algorithms
We describe numerical techniques used in the construction of our 4th order
evolution for the full Einstein equations, and assess the accuracy of
representative solutions. The code is based on a null gauge with a
quasi-spherical radial coordinate, and simulates the interaction of a single
black hole with gravitational radiation. Techniques used include spherical
harmonic representations, convolution spline interpolation and filtering, and
an RK4 "method of lines" evolution. For sample initial data of "intermediate"
size (gravitational field with 19% of the black hole mass), the code is
accurate to 1 part in 10^5, until null time z=55 when the coordinate condition
breaks down.Comment: Latex, 38 pages, 29 figures (360Kb compressed
On the existence of Killing vector fields
In covariant metric theories of coupled gravity-matter systems the necessary
and sufficient conditions ensuring the existence of a Killing vector field are
investigated. It is shown that the symmetries of initial data sets are
preserved by the evolution of hyperbolic systems.Comment: 9 pages, no figure, to appear in Class. Quant. Gra
Static self-gravitating many-body systems in Einstein gravity
We consider the problem of constructing static, elastic, many-body systems in
Einstein gravity. The solutions constructed are deformations of static
many-body configurations in Newtonian gravity. No symmetry assumptions are
made.Comment: 15 page
Quantization of Gauge Field Theories on the Front-Form without Gauge Constraints I : The Abelian Case
Recently, we have proposed a new front-form quantization which treated both
the and the coordinates as front-form 'times.' This
quantization was found to preserve parity explicitly. In this paper we extend
this construction to local Abelian gauge fields . We quantize this theory using
a method proposed originally by Faddeev and Jackiw . We emphasize here the
feature that quantizing along both and , gauge theories does not
require extra constraints (also known as 'gauge conditions') to determine the
solution uniquely.Comment: 18 pages, phyzz
Symmetries of spacetime and their relation to initial value problems
We consider covariant metric theories of coupled gravity-matter systems
satisfying the following two conditions: First, it is assumed that, by a
hyperbolic reduction process, a system of first order symmetric hyperbolic
partial differential equations can be deduced from the matter field equations.
Second, gravity is supposed to be coupled to the matter fields by requiring
that the Ricci tensor is a smooth function of the basic matter field variables
and the metric. It is shown then that the ``time'' evolution of these type of
gravity-matter systems preserves the symmetries of initial data specifications.Comment: 12 pages, to appear in Class. Quant. Gra
Ghost points in inverse scattering constructions of stationary Einstein metrics
We prove a removable singularities theorem for stationary Einstein equations,
with useful implications for constructions of stationary solutions using
soliton methods
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
Uniqueness Theorem for Static Black Hole Solutions of sigma-models in Higher Dimensions
We prove the uniqueness theorem for self-gravitating non-linear sigma-models
in higher dimensional spacetime. Applying the positive mass theorem we show
that Schwarzschild-Tagherlini spacetime is the only maximally extended, static
asymptotically flat solution with non-rotating regular event horizon with a
constant mapping.Comment: 5 peges, Revtex, to be published in Class.Quantum Gra