2,322 research outputs found
Gravitational field of domain wall in Lyra geometry
In this paper, we study the domain wall with time dependent displacement
vectors based on Lyra geometry in normal gauge i.e. displacement vector . The field theoretic energy momentum tensor is
considered with zero pressure perpendicular to the wall. We find an exact
solutions of Einstein equation for a scalar field with a potential
describing the gravitational field of a plane symmetric domain wall.
We have seen that the hyper surfaces parallel to the wall ()
are three dimensional de-sitter spaces. It is also shown that the gravitational
field experienced by test particle is attractive.Comment: 11 pages, 6 figures; Submitted in Astrophysics and Space Science
after minor revisio
Thin Domain Walls in Lyra Geometry
This paper studies thin domain walls within the frame work of Lyra Geometry.
We have considered two models. First one is the thin domain wall with
negligible pressures perpendicular and transverse direction to the wall and
secondly, we take a particular type of thin domain wall where the pressure in
the perpendicular direction is negligible but transverse pressures are existed.
It is shown that the thin domain walls have no particle horizon and the
gravitational force due to them is attractive.Comment: 8 pages, typos are corrected, published Astrophysics and Space
Sciences 305, 337 (2006
Vacuumless topological defects in Lyra geometry
Few years ago, Cho and Vilenkin have proposed that topological defects can
arise in symmetry breaking models without having degenerate vacua. These types
of defects are known as vacuumless defects. In the present work, the
gravitational field of a vacuumless global string and global monopole have been
investigated in the context of Lyra geometry. We find the metric of the
vacuumless global string and global monopole in the weak field approximations.
It has been shown that the vacuumless global string can have repulsive whereas
global monopole exerts attractive gravitational effects on a test particle. It
is dissimilar to the case studied in general relativity.Comment: 14 pages, 9 figures. To appear in Astrophys.Space.Sc
Thin shell wormhole due to dyadosphere of a charged black hole
To explain Gamma Ray Bursts, Ruffini argued that the event horizon of a
charged black hole is surrounded by a special region called, the Dyadosphere
where electric field exceeds the critical value for pair
production. In the present work, we construct a thin shell wormhole by
performing a thought surgery between two dadospheres. Several physical
properties of this thin shell wormhole have been analyzed.Comment: 10 pages, 2 figures. Accepted in Mod.Phys.Lett.
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