189,517 research outputs found
Kinematic Self-Similar Solutions of Locally Rotationally Symmetric Spacetimes
This paper contains locally rotationally symmetric kinematic self-similar
perfect fluid and dust solutions. We consider three families of metrics which
admit kinematic self-similar vectors of the first, second, zeroth and infinite
kinds, not only for the tilted fluid case but also for the parallel and
orthogonal cases. It is found that the orthogonal case gives contradiction both
in perfect fluid and dust cases for all the three metrics while the tilted case
reduces to the parallel case in both perfect fluid and dust cases for the
second metric. The remaining cases give self-similar solutions of different
kinds. We obtain a total of seventeen independent solutions out of which two
are vacuum. The third metric yields contradiction in all the cases.Comment: 17 pages, accepted for publication Brazilian J. Physic
Rotating metrics admitting non-perfect fluids in General Relativity
In this paper, by applying Newman-Janis algorithm in spherical symmetric
metrics, a class of embedded rotating solutions of field equations is
presented. These solutions admit non-perfect fluidsComment: LaTex, 39 page
Godel-type space-time metrics
A simple group theoretic derivation is given of the family of space-time
metrics with isometry group SO(2,1) X SO(2) X R first described by Godel, of
which the Godel stationary cosmological solution is the member with a
perfect-fluid stress-energy tensor. Other members of the family are shown to be
interpretable as cosmological solutions with a electrically charged perfect
fluid and a magnetic field.Comment: Heavly rewritten respect to the orginal version, corrected some typos
due to files transfer in the last submitted versio
All Static Circularly Symmetric Perfect Fluid Solutions of 2+1 Gravity
Via a straightforward integration of the Einstein equations with cosmological
constant, all static circularly symmetric perfect fluid 2+1 solutions are
derived. The structural functions of the metric depend on the energy density,
which remains in general arbitrary. Spacetimes for fluids fulfilling linear and
polytropic state equations are explicitly derived; they describe, among others,
stiff matter, monatomic and diatomic ideal gases, nonrelativistic degenerate
fermions, incoherent and pure radiation. As a by--product, we demonstrate the
uniqueness of the constant energy density perfect fluid within the studied
class of metrics. A full similarity of the perfect fluid solutions with
constant energy density of the 2+1 and 3+1 gravities is established.Comment: revtex4, 8 page
Self-similar static solutions admitting a two-space of constant curvature
A recent result by Haggag and Hajj-Boutros is reviewed within the framework
of self-similar space-times, extending, in some sense, their results and
presenting a family of metrics consisting of all the static spherically
symmetric perfect fluid solutions admitting a homothety.Comment: 6 page
Modeling usual and unusual anisotropic spheres
In this paper, we study anisotropic spheres built from known static spherical
solutions. In particular, we are interested in the physical consequences of a
"small" departure from a physically sensible configuration. The obtained
solutions smoothly depend on free parameters. By setting these parameters to
zero, the starting seed solution is regained. We apply our procedure in detail
by taking as seed solutions the Florides metrics, and the Tolman IV solution.
We show that the chosen Tolman IV, and also Heint IIa Durg IV,V perfect fluid
solutions, can be used to generate a class of parametric solutions where the
anisotropic factor has features recalling boson stars. This is an indication
that boson stars could emerge by "perturbing" appropriately a perfect fluid
solution (at least for the seed metrics considered). Finally, starting with
Tolman IV, Heint IIa and Durg IV,V solutions, we build anisotropic
gravastar-like sources with the appropriate boundary conditions.Comment: Final version published in IJMP
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