7 research outputs found
Gravitational Collapse: Expanding and Collapsing Regions
We investigate the expanding and collapsing regions by taking two well-known
spherically symmetric spacetimes. For this purpose, the general formalism is
developed by using Israel junction conditions for arbitrary spacetimes. This
has been used to obtain the surface energy density and the tangential pressure.
The minimal pressure provides the gateway to explore the expanding and
collapsing regions. We take Minkowski and Kantowski-Sachs spacetimes and use
the general formulation to investigate the expanding and collapsing regions of
the shell.Comment: 12 pages, 4 figures, accepted for publication in Gen. Relativ. Gra
Gravitational Collapse in Higher Dimensional Husain Space-Time
We investigate exact solution in higher dimensional Husain model for a null
fluid source with pressure and density are related by the following
relations (i) , (ii) (variable
modified Chaplygin) and (iii) (polytropic). We have studied
the nature of singularity in gravitational collapse for the above equations of
state and also for different choices of the of the parameters and
namely, (i) , constant (generalized Chaplygin), (ii) constant
(modified Chaplygin). It is found that the nature of singularity is independent
of these choices of different equation of state except for variable Chaplygin
model. Choices of various parameters are shown in tabular form. Finally,
matching of Szekeres model with exterior Husain space-time is done.Comment: 12 latex pages, No figure, RevTex styl
Junction Conditions and Consequences of Quasi-Spherical Space-Time with Electro-Magnetic Field and Vaidya Matric
In this work the junction conditions between the exterior
Reissner-Nordstrom-Vaidya space-time with the interior quasi-spherical Szekeres
space-time have been studied for analyzing gravitational collapse in the
presence of a magneto-hydrodynamic fluid undergoing dissipation in the form of
heat flow. We have discussed about the apparent horizon and have evaluated the
time difference between the formation of apparent horizon and central
singularity.Comment: 8 latex pages, RevTex style, no figure
Gravitational Collapse in Generalized Vaidya Space-Time for Lovelock Gravity Theory
In this work, we have assumed the generalized Vaidya solution in Lovelock
theory of gravity in -dimensions. It has been shown that Gauss-Bonnet
gravity, dimensionally continued Lovelock gravity and pure Lovelock gravity can
be constructed by suitable choice of parameters. We have investigated the
occurrence of singularities formed by the gravitational collapse in above three
particular forms of Lovelock theory of gravity. The dependence of the nature of
singularity on the existence of radial null geodesic for Vaidya space-time has
been specially considered. In all the three models, we have shown that the
nature of singularities (naked singularity or black hole) completely depend on
the parameters. Choices of various parameters are shown in tabular form. In
Gauss-Bonnet gravity theory, it can be concluded that the possibility of naked
singularity increases with increase in dimensions. In dimensionally continued
Lovelock gravity, the naked singularity is possible for odd dimensions for
several values of parameters. In pure Lovelock gravity, only black hole forms
due to the gravitational collapse for any values of parameters. It has been
shown that when accretion is taking place on a collapsing object, it is highly
unlikely to get a black hole. Finally on considering the phantom era in the
expanding universe it is observed that there is no possibility of formation of
a black hole if we are in the Gauss-Bonnet gravity considering the accreting
procedure upon a collapsing object.Comment: 11 page