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The behaviors of quantum stress tensor for the scalar field on the classical background of spherical dust collapse is studied. In the previous works diverging flux of quantum radiation was predicted. We use the exact expressions in a 2D…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Hideo Iguchi , Tomohiro Harada

There are many solutions to the Einstein field equations that demonstrate naked singularity (NS) formation after regular evolution. It is possible, however, that such a quantum effect as particle creation prevents NSs from forming. We…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Umpei Miyamoto , Hideki Maeda , Tomohiro Harada

We analyze the stability of the Cauchy horizon associated with a globally naked, shell-focussing singularity arising from the complete gravitational collapse of a spherical dust cloud. In previous work, we have studied the dynamics of…

General Relativity and Quantum Cosmology · Physics 2018-01-09 Néstor Ortiz , Olivier Sarbach

It has been suggested that a naked singularity may be a good candidate for a strong gravitational wave burster. The naked singularity occurs in the generic collapse of an inhomogeneous dust ball. We study odd-parity mode of gravitational…

General Relativity and Quantum Cosmology · Physics 2011-07-19 Hideo Iguchi , Tomohiro Harada , Ken-ichi Nakao

Generalizing earlier results of Joshi and Dwivedi (Commun. Math. Phys. 146, 333 (1992); Lett. Math. Phys. 27, 235 (1993)), we analyze here the spherically symmetric gravitational collapse of a matter cloud with a general form of matter for…

General Relativity and Quantum Cosmology · Physics 2009-10-22 I. H. Dwivedi , P. S. Joshi

Spherical dust collapse generally forms a shell focusing naked singularity at the symmetric center. This naked singularity is massless. Further the Newtonian gravitational potential and speed of the dust fluid elements are everywhere much…

General Relativity and Quantum Cosmology · Physics 2009-10-31 K. Nakao , H. Iguchi , T. Harada

We investigate the occurrence and nature of naked singularity for the inhomogeneous gravitational collapse of Tolman-Bondi dust clouds.It is shown that the naked singularities form at the center of the collapsing cloud in a wide class of…

General Relativity and Quantum Cosmology · Physics 2009-10-22 P. S. Joshi , I. H. Dwivedi

The unbounded center of mass (CM) energy of oppositely moving colliding particles near horizon emerge also in 1+1- dimensional Horava-Lifshitz gravity. This theory has imprints of renormalizable quantum gravity characteristics in accordance…

General Relativity and Quantum Cosmology · Physics 2017-01-17 M. Halilsoy , A. Ovgun

It has recently been pointed out that, under certain conditions, the energy of particles accelerated by black holes in the center-of-mass frame can become arbitrarily high. In this paper, we study the collision of two particles in the case…

High Energy Physics - Theory · Physics 2017-04-04 Pu-Jian Mao , Ran Li , Lin-Yu Jia , Ji-Rong Ren

This article gives an elementary review of gravitational collapse and the cosmic censorship hypothesis. Known models of collapse resulting in the formation of black holes and naked singularities are summarized. These models, when taken…

General Relativity and Quantum Cosmology · Physics 2009-10-31 T. P. Singh

A spherical dust cloud which is initially at rest and which has a monotonously decaying density profile collapses and forms a shell-focussing singularity. Provided the density profile is not too flat, meaning that its second radial…

General Relativity and Quantum Cosmology · Physics 2014-06-17 Néstor Ortiz , Olivier Sarbach

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

In this study, the particle motion around the naked singularity and black hole of Kerr-Newman spacetime is investigated with a special attention on the closed timelike orbits. It is found that both in the naked singularity (NS) and in black…

General Relativity and Quantum Cosmology · Physics 2024-10-08 Ayanendu Dutta , Dhritimalya Roy , Subenoy Chakraborty

There are models of gravitational collapse in classical general relativity which admit the formation of naked singularities as well as black holes. These include fluid models as well as models with scalar fields as matter. Even if fluid…

General Relativity and Quantum Cosmology · Physics 2007-05-23 T. P. Singh

A distinguishable physical property between a naked singularity and a black-hole, formed during a gravitational collapse has important implications for both experimental and theoretical relativity. We examine the energy radiated during the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 I. H. Dwivedi

Continued gravitational collapse gives rise to curvature singularities. If a curvature singularity is globally naked then the space-time may be causally future ill-behaved admitting closed time-like or null curves which extend to asymptotic…

General Relativity and Quantum Cosmology · Physics 2010-11-11 F. de Felice

We examine here the acceleration of particles and high energy collisions in the the Janis-Newman- Winicour (JNW) spacetime, which is an extension of the Schwarzschild geometry when a massless scalar field is included. We show that while the…

General Relativity and Quantum Cosmology · Physics 2012-05-16 Mandar Patil , Pankaj S. Joshi

We will describe here the structure of singularity forming in gravitational collapse of spherically symmetric inhomogeneous dust. Such a collapse is described by the Tolman-Bondi-Lema{\^i}tre metric. The main new result here relates, in a…

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

A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in the presence of a pure cosmological…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Kengo Maeda , Takashi Torii , Makoto Narita

A new simple and general explanation of the effect of acceleration of particles by black holes to infinite energies in the centre of mass frame is suggested. It is based on kinematics of particles moving near the horizon. This effect arises…

General Relativity and Quantum Cosmology · Physics 2011-08-12 O. B. Zaslavskii