94 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
Anisotropic generalization of well-known solutions describing relativistic self-gravitating fluid systems: An algorithm
We present an algorithm to generalize a plethora of well-known solutions to
Einstein field equations describing spherically symmetric relativistic fluid
spheres by relaxing the pressure isotropy condition on the system. By suitably
fixing the model parameters in our formulation, we generate closed-form
solutions which may be treated as anisotropic generalization of a large class
of solutions describing isotropic fluid spheres. From the resultant solutions,
a particular solution is taken up to show its physical acceptability. Making
use of the current estimate of mass and radius of a known pulsar, the effects
of anisotropic stress on the gross physical behaviour of a relativistic compact
star is also highlighted.Comment: To appear in Eur. Phys. J.
Mixed potentials in radiative stellar collapse
We study the behaviour of a radiating star when the interior expanding,
shearing fluid particles are traveling in geodesic motion. We demonstrate that
it is possible to obtain new classes of exact solutions in terms of elementary
functions without assuming a separable form for the gravitational potentials or
initially fixing the temporal evolution of the model unlike earlier treatments.
A systematic approach enables us to write the junction condition as a Riccati
equation which under particular conditions may be transformed into a separable
equation. New classes of solutions are generated which allow for mixed spatial
and temporal dependence in the metric functions. We regain particular models
found previously from our general classes of solutions.Comment: 10 pages, To appear in J. Math. Phy
Charged anisotropic matter with linear equation of state
We consider the general situation of a compact relativistic body with
anisotropic pressures in the presence of the electromagnetic field. The
equation of state for the matter distribution is linear and may be applied to
strange stars with quark matter. Three classes of new exact solutions are found
to the Einstein-Maxwell system. This is achieved by specifying a particular
form for one of the gravitational potentials and the electric field intensity.
We can regain anisotropic and isotropic models from our general class of
solution. A physical analysis indicates that the charged solutions describe
realistic compact spheres with anisotropic matter distribution. The equation of
state is consistent with dark energy stars and charged quark matter
distributions. The masses and central densities correspond to realistic stellar
objects in the general case when anisotropy and charge are present.Comment: 17 pages, To appear in Class. Quantum Gra
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