A new framework for studying spherically symmetric static solutions in f(R) gravity (2009)
Nzioki, Anne Marie, Carloni, Sante, Goswami, Rituparno, Dunsby, Peter K. S.
We develop a new covariant formalism to treat spherically symmetric spacetimes in f(R) theories of gravity. Using this formalism we derive the general equations for a static and spherically symmetric...
On the co-existence of matter dominated and accelerating solutions in f(G)-gravity (2009)
Goheer, Naureen, Goswami, Rituparno, Dunsby, Peter K. S., Ananda, Kishore
Working within the theory of modified Gauss-Bonnet gravity, we show that FLRW--like power--law solutions only exist for a very special class of f(G)theories. Furthermore, we point out that any...
Dynamics of f(R)-cosmologies containing Einstein static models (2008)
Goheer, Naureen, Goswami, Rituparno, Dunsby, Peter K. S.
We study the dynamics of homogeneous isotropic FRW cosmologies with positive spatial curvature in $f(R)$-gravity, paying special attention to the existence of Einstein static models and only study...
An eternally collapsing scalar field universe (2008)
Bhattacharya, Swastik, Goswami, Rituparno, Joshi, Pankaj
We study here the evolution of a massless scalar field universe, developing from a regular initial spacelike surface. The Einstein equations and regularity and boundary conditions governing the same...
Goswami, Rituparno, Goheer, Naureen, Dunsby, Peter K. S.
We investigate whether or not an Einstein Static universe is a solution to the cosmological equations in $f(R)$ gravity. It is found that only one class of $f(R)$ theories admits an Einstein Static...
On trapped surface formation in gravitational collapse II (2007)
Joshi, Pankaj S., Goswami, Rituparno
Further to our consideration on trapped surfaces in gravitational collapse, where pressures were allowed to be negative while satisfying weak energy condition to avoid trapped surface formation, we...
Gravitational collapse of dustlike matter with heat flux (2007)
We present a new class of solutions to Einstein equations for the spherical collapse of dustlike matter coupled with heat flux. In this family of solutions spacetime shear is necessarily non-zero....
Surface Geometry of 5D Black Holes and Black Rings (2006)
Frolov, Valeri P., Goswami, Rituparno
We discuss geometrical properties of the horizon surface of five-dimensional rotating black holes and black rings. Geometrical invariants characterizing these 3D geometries are calculated. We obtain...
Spherical gravitational collapse in N-dimensions (2006)
Goswami, Rituparno, Joshi, Pankaj S
We investigate here spherically symmetric gravitational collapse in a spacetime with an arbitrary number of dimensions and with a general {\it type I} matter field, which is a broad class that...
Quantum evaporation of a naked singularity (2005)
Goswami, Rituparno, Joshi, Pankaj S., Singh, Parampreet
We investigate here quantum effects in gravitational collapse of a scalar field model which classically leads to a naked singularity. We show that non-perturbative semi-classical modifications near...
Goswami, Rituparno, Joshi, Pankaj S.
The occurrence of a spacetime singularity indicates the breakdown of Einstein gravitation theory in these extreme regimes. We consider here the singularity issue and various black hole paradoxes at...
A black hole mass threshold from non-singular quantum gravitational collapse (2005)
Bojowald, Martin, Goswami, Rituparno, Maartens, Roy, Singh, Parampreet
Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a toy model of a collapsing homogeneous...
Gravitational collapse in asymptotically Anti-de Sitter/de Sitter backgrounds (2005)
Madhav, T. Arun, Goswami, Rituparno, Joshi, Pankaj S.
We study here the gravitational collapse of a matter cloud with a non-vanishing tangential pressure in the presence of a non-zero cosmological term. Conditions for bounce and singularity formation...
Cosmic Censorship in Higher dimension II (2005)
Mahajan, Ashutosh, Goswami, Rituparno, Joshi, Pankaj S.
Generalizing earlier results on dust collapse in higher dimensions, we show here that cosmic censorship can be restored in gravitational collapse with tangential pressure present if we take the...
A black hole mass threshold from non-singular quantum gravitational collapse (2005)
Bojowald,Martin, Goswami,Rituparno, Maartens,Roy, Singh,Parampreet
Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing...
A black hole mass threshold from non-singular quantum gravitational collapse (2005)
Bojowald, Martin, Goswami, Rituparno, Maartens, Roy, Singh, Parampreet
Quantum gravity is expected to remove the classical singularity that arises as the end-state of gravitational collapse. To investigate this, we work with a simple toy model of a collapsing...
Naked Singularity formation in scalar field collapse (2004)
Goswami, Rituparno, Joshi, Pankaj S
We construct here a class of collapsing scalar field models with a non-zero potential, which result in a naked singularity as collapse end state. The weak energy condition is satisfied by the...
A Time-Like Naked Singularity (2004)
Goswami, Rituparno, Joshi, Pankaj S., Vaz, Cenalo, Witten, Louis
We construct a class of spherically symmetric collapse models in which a naked singularity may develop as the end state of collapse. The matter distribution considered has negative radial and...
Gravitational collapse of an isentropic perfect fluid with a linear equation of state (2004)
Goswami, Rituparno, Joshi, Pankaj S
We investigate here the gravitational collapse end states for a spherically symmetric perfect fluid with an equation of state $p=k\rho$. It is shown that given a regular initial data in terms of the...
Cosmic Censorship in Higher Dimensions (2004)
Goswami, Rituparno, Joshi, Pankaj S
We show that the naked singularities arising in dust collapse from smooth initial data (which include those discovered by Eardley and Smarr, Christodoulou, and Newman) are removed when we make...
Gravitational collapse from smooth initial data with vanishing radial pressure (2003)
Mahajan, Ashutosh, Goswami, Rituparno, Joshi, Pankaj S.
We study here the spherical gravitational collapse assuming initial data to be necessarily smooth, as motivated by the requirements based on physical reasonableness. A tangential pressure model is...
Black hole formation in perfect fluid collapse (2003)
Goswami, Rituparno, Joshi, Pankaj S
We construct here a special class of perfect fluid collapse models which generalizes the homogeneous dust collapse solution in order to include non-zero pressures and inhomogeneities into evolution....
The critical role of shear in gravitational collapse (2003)
Joshi, Pankaj S., Goswami, Rituparno, Dadhich, Naresh
We investigate here how the shearing effects present within a collapsing matter cloud influence the outcome of gravitational collapse in terms of formation of either a black hole or a naked...
Spherical Dust Collapse in Higher Dimensions (2002)
Goswami, Rituparno, Joshi, Pankaj S
We consider here the question if it is possible to recover cosmic censorship when a transition is made to higher dimensional spacetimes, by studying the spherically symmetric dust collapse in an...
What role pressures play to determine the final end-state of gravitational collapse? (2002)
Goswami, Rituparno, Joshi, Pankaj S
We examine here in what way the pressures affect the final fate of a continual gravitational collapse. It is shown that the presence of a non-vanishing pressure gradient in the collapsing cloud...
Role of initial data in spherical collapse (2002)
Joshi, Pankaj S., Goswami, Rituparno
We bring out here the role of initial data in causing the black hole and naked singularity phases as the final end state of a continual gravitational collapse. The collapse of a type I general matter...