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We study the formation of the (noncommutative) Schwarzschild black hole from collapsing shell {of the} generalized matters containing polytropic and Chaplygin gas. We show that this collapsing shell depending on various parameters forms…

General Relativity and Quantum Cosmology · Physics 2010-05-12 John J. Oh , Chanyong Park

We analyze here the issue of local versus the global visibility of a singularity that forms in gravitational collapse of a dust cloud, which has important implications for the weak and strong versions of the cosmic censorship hypothesis. We…

General Relativity and Quantum Cosmology · Physics 2015-06-25 S. S. Deshingkar , S. Jhingan , P. S. Joshi

We compute the dynamics of particles and strings falling into smooth horizonless spacetimes that match the Schwarzschild black hole but replace its horizon with a smooth cap in supergravity. The cap consists of a regular topological…

High Energy Physics - Theory · Physics 2025-06-09 Pierre Heidmann , Gela Patashuri

Previously, it was noticed that in some space-times with Killing horizons some curvature components, responsible for tidal forces, small or even zero in the static frame, become enhanced from the viewpoint of a falling observer. This leads…

General Relativity and Quantum Cosmology · Physics 2025-05-01 H. V. Ovcharenko , O. B. Zaslavskii

We show that, in principle, a slowly evolving gravitationally collapsing perfect fluid cloud can asymptotically settle to a static spherically symmetric equilibrium configuration with a naked singularity at the center. We consider one such…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Pankaj S. Joshi , Daniele Malafarina , Ramesh Narayan

Motivated by the recent argument that in the TeV-scale gravity trans-Planckian domains of spacetime as effective naked singularities would be generated by high-energy particle (and black-hole) collisions, we investigate the quantum particle…

General Relativity and Quantum Cosmology · Physics 2012-03-06 Umpei Miyamoto , Hiroya Nemoto , Masahiro Shimano

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 massive matter cloud is governed by the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Pankaj S. Joshi

In our previous work [Van de Moortel, The breakdown of weak null singularities, Duke Mathematical Journal 172 (15), 2957-3012, 2023], we showed that dynamical black holes formed in charged spherical collapse generically feature both a null…

General Relativity and Quantum Cosmology · Physics 2025-10-13 Maxime Van de Moortel

It was believed that when gravitational, electromagnetic and scalar waves interact, a spacelike curvature singularity or Cauchy horizon develops because of mutual focusing. We show with an exact solution that the collision of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ozay Gurtug , Mustafa Halilsoy

We analyze the redshift suffered by photons originating from an external source, traversing a collapsing dust cloud and finally being received by an asymptotic observer. In addition, we study the shadow that the collapsing cloud casts on…

General Relativity and Quantum Cosmology · Physics 2015-09-10 Néstor Ortiz , Olivier Sarbach , Thomas Zannias

A distinguishable and observable physical property of Naked Singular Regions of the spacetime formed during a gravitational collapse has important implications for both experimental and theoretical relativity. We examine here whether energy…

General Relativity and Quantum Cosmology · Physics 2011-08-08 S. Jhingan , I. H. Dwivedi , S. Barve

We present here an overview of our basic understanding and recent developments on spacetime singularities in the Einstein theory of gravity. Several issues related to physical significance and implications of singularities are discussed.…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Pankaj S. Joshi

We show that algebraically special modes lead to the instability of naked singularity spacetimes with negative mass. Four-dimensional negative-mass Schwarzschild and Schwarzschild-de Sitter spacetimes are unstable. Stability of the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Vitor Cardoso , Marco Cavaglia

We investigate the end state of gravitational collapse of null fluid in higher dimensional space-times. Both naked singularities and black holes are shown to be developing as final outcome of the collapse. The naked singularity spectrum in…

General Relativity and Quantum Cosmology · Physics 2009-11-07 S. G. Ghosh , Naresh Dadhich

Naked singularity occurs in the gravitational collapse of an inhomogeneous dust ball from an initial density profile which is physically reasonable. We show that explosive radiation is emitted during the formation process of the naked…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Tomohiro Harada , Hideo Iguchi , Ken-ichi Nakao

This paper investigates tidal forces in multidimensional spherically symmetric spacetimes. We consider geodesic deviation equation in Schwarzschild-Tangherlini metric and its electrically charged analog. It was shown that for radial…

General Relativity and Quantum Cosmology · Physics 2023-01-09 V. P. Vandeev , A. N. Semenova

We investigate the tidal forces exerted by a spherically symmetric static parametrized black hole. Our analysis reveals that the radial and angular components of the tidal forces exerted by the black hole can exhibit both positive and…

General Relativity and Quantum Cosmology · Physics 2023-11-09 Bobir Toshmatov , Bobomurat Ahmedov

We study the complete gravitational collapse of a class of spherically symmetric inhomogeneous perfect fluid models obtained by introducing small radial perturbations in an otherwise homogeneous matter cloud. Our aim here is to study the…

General Relativity and Quantum Cosmology · Physics 2016-03-10 Seema Satin , Daniele Malafarina , Pankaj S. Joshi

It is generally believed that the shadows of either a black hole or naked singularity arise due to photon spheres developing in these spacetimes. Here we propose a new spherically symmetric naked singularity spacetime solution of Einstein…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Ashok B. Joshi , Dipanjan Dey , Pankaj S. Joshi , Parth Bambhaniya

A naked singularity is formed by the collapse of a Sine-Gordon soliton in 1+1 dimensional dilaton gravity with a negative cosmological constant. We examine the quantum stress tensor resulting from the formation of the singularity.…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Cenalo Vaz , Louis Witten