2,042 research outputs found
Radiating relativistic matter in geodesic motion
We study the gravitational behaviour of a spherically symmetric radiating
star when the fluid particles are in geodesic motion. We transform the
governing equation into a simpler form which allows for a general analytic
treatment. We find that Bernoulli, Riccati and confluent hypergeometric
equations are possible. These admit solutions in terms of elementary functions
and special functions. Particular models contain the Minkowski spacetime and
the Friedmann dust spacetime as limiting cases. Our infinite family of
solutions contains specific models found previously. For a particular metric we
briefly investigate the physical features, derive the temperature profiles and
plot the behaviour of the casual and acasual temperatures.Comment: 15 pages, to appear in J. Math. Phy
Conformal symmetries of spherical spacetimes
We investigate the conformal geometry of spherically symmetric spacetimes in
general without specifying the form of the matter distribution. The general
conformal Killing symmetry is obtained subject to a number of integrability
conditions. Previous results relating to static spacetimes are shown to be a
special case of our solution. The general inheriting conformal symmetry vector,
which maps fluid flow lines conformally onto fluid flow lines, is generated and
the integrability conditions are shown to be satisfied. We show that there
exists a hypersurface orthogonal conformal Killing vector in an exact solution
of Einstein's equations for a relativistic fluid which is expanding,
accelerating and shearing.Comment: 8 pages, To appear in Int. J. Theor. Phy
Anisotropic fluid spheres of embedding class one using Karmarkar condition
We obtain a new anisotropic solution for spherically symmetric spacetimes by
analysing of the Karmarkar embedding condition. For this purpose we construct a
suitable form of one of the gravitational potentials to obtain a closed form
solution. This form of the remaining gravitational potential allows us to solve
the embedding equation and integrate the field equations. The resulting new
anisotropic solution is well behaved which can be utilized to construct
realistic static fluid spheres. Also we estimated masses and radii of fluid
spheres for LMC X-4 and EXO 1785-248 by using observational data sets values.
The obtained masses and radii show that our anisotropic solution can represent
fluid spheres to a very good degree of accuracy.Comment: 16 pages, 11 figure
A class of charged relativistic spheres
We find a new class of exact solutions to the Einstein-Maxwell equations
which can be used to model the interior of charged relativistic objects. These
solutions can be written in terms of special functions in general; for
particular parameter values it is possible to find solutions in terms of
elementary functions. Our results contain models found previously for uncharged
neutron stars and charged isotropic spheres.Comment: 11 pages, To appear in Mathematical and Computational Application
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