Accelerated cosmic expansion in a scalar-field universe (2009)
Bhattacharya, Swastik, Joshi, Pankaj S., Nakao, Ken-ichi
We consider here a spherically symmetric but inhomogeneous universe filled with a massless scalar field. The model obeys two constraints. The first one is that the gradient of the scalar field is...
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...
Critical Collapse of Einstein Cluster (2007)
Mahajan, Ashutosh, Harada, Tomohiro, Joshi, Pankaj S., Nakao, Ken-ichi
We observe critical phenomena in spherically symmetric gravitational collapse of Einstein Cluster. We show analytically that the collapse evolution ends either in formation of a black hole or in...
On the genericity of spacetime singularities (2007)
We consider here the genericity aspects of spacetime singularities that occur in cosmology and in gravitational collapse. The singularity theorems (that predict the occurrence of singularities in...
The structure of non-spacelike curves from a spacetime singularity (2006)
We investigate here the causal structure of spacetime in the vicinity of a spacetime singularity. The particle and energy emission from such ultra-dense regions forming in gravitational collapse of a...
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...
Mahajan, Ashutosh, Joshi, Pankaj S.
We examine spherical gravitational collapse of a matter model with vanishing radial pressure and non-zero tangential pressure. It is seen analytically that the collapsing cloud either forms a black...
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...
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...
Gravitational Collapse End States (2004)
Recent developments on the final state of a gravitationally collapsing massive matter cloud are summarized and reviewed here. After a brief background on the problem, we point out how the black hole...
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...
Gravitational Collapse End States (2004)
Recent developments on the final state of a gravitationally collapsing massive matter cloud are summarized and reviewed here. After a brief background on the problem, we point out how the black hole...
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...
Cosmic Censorship: A Current Perspective (2002)
End state of gravitational collapse and the related cosmic censorship conjecture continue to be amongst the most important open problems in gravitation physics today. My purpose here is to bring out...
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...
Why do naked singularities form in gravitational collapse? (2001)
Joshi, Pankaj S., Dadhich, Naresh, Maartens, Roy
We investigate what are the key physical features that cause the development of a naked singularity, rather than a black hole, as the end-state of spherical gravitational collapse. We show that...
Gravitational Collapse: The Story so far (2000)
An outstanding problem in gravitation theory and relativistic astrophysics today is to understand the final outcome of an endless gravitational collapse. Such a continual collapse would take place...
Initial data and spherical dust collapse (2000)
Mena, Filipe C., Tavakol, Reza, Joshi, Pankaj S.
By considering families of radial null geodesics, we study the subsets of initial data that lead to naked singularities and black holes in inhomogeneous spherical dust collapse. We introduce the...
Naked strong curvature singularities in Szekeres space-times (1996)
Joshi, Pankaj S., Krolak, Andrzej
We investigate the occurrence and nature of naked singularities in the Szekeres space-times. These space-times represent irrotational dust. They do not have any Killing vectors and they are...
Naked strong curvature singularities in Szekeres space-times (1996)
Pankaj S. Joshi, Andrzej Królak
We investigate the occurrence and nature of naked singularities in the Szekeres space-times. These space-times represent irrotational dust. They do not have any Killing vectors and they are...
Naked Singularities as Possible Candidates for Gamma-ray Bursters (1992)
Chakrabarti, Sandip K., Joshi, Pankaj S.
Naked singularities appear naturally in dynamically evolving solutions of Einstein equations involving gravitational collapse of radiation, dust and perfect fluids, provided the rate of accretion is...