5,031 research outputs found
Killing vectors and anisotropy
We consider an action that can generate fluids with three unequal stresses
for metrics with a spacelike Killing vector. The parameters in the action are
directly related to the stress anisotropies. The field equations following from
the action are applied to an anisotropic cosmological expansion and an
extension of the Gott-Hiscock cosmic string
Electrovac -waves
New exact solutions of the Einstein-Maxwell field equations that describe
-waves are presented
A spacetime dual to the NUT spacetime
By decomposing the Riemann curvature into electric and magnetic parts, a
duality transformation, which involves interchange of active and passive
electric parts, has recently been proposed. It was shown that the Schwarzschild
solution is dual to the one that describes the Schwarzschild particle with
cloud of string dust or a global monopole. Following the same procedure we
obtain the solution dual to the NUT spacetime.Comment: 10 pages, Latex. Accepted for publication in Classical and Quantum
Gravit
Gravitational Lensing Bound On The Average Redshift Of Gamma Ray Bursts In Models With Evolving Lenses
Identification of gravitationally lensed Gamma Ray Bursts (GRBs) in the BATSE
4B catalog can be used to constrain the average redshift of the GRBs.
In this paper we investigate the effect of evolving lenses on the of
GRBs in different cosmological models of universe. The cosmological parameters
$\Omega$ and $\Lambda$ have an effect on the of GRBs. The other factor
which can change the of GRBs is higher in evolving model of galaxies as compared to
non-evolving models of galaxies.Comment: 23 pages,one plain LaTeX file with three postscript figures This is
modified version with recent BATSE efficiency parameter and with the latest F
paramete
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