314 research outputs found
Analytic derivation of the map of null rays passing near a naked singularity
Recently the energy emission from a naked singularity forming in spherical
dust collapse has been investigated. This radiation is due to the particle
creation in a curved spacetime. In this discussion, the central role is played
by the mapping formula between the incoming and the outgoing null coordinates.
For the self-similar model, this mapping formula has been derived analytically.
But for the model with density profile, the mapping formula has
been obtained only numerically. In the present paper, we argue that the
singular nature of the mapping is determined by the local geometry around the
point at which the singularity is first formed. If this is the case, it would
be natural to expect that the mapping formula can be derived analytically. In
the present paper, we analytically rederive the same mapping formula for the
model with density profile that has been earlier derived using a
numerical technique.Comment: 4 pages, submitted to Phys. Rev.
Quantum general relativity and Hawking radiation
In a previous paper we have set up the Wheeler-DeWitt equation which
describes the quantum general relativistic collapse of a spherical dust cloud.
In the present paper we specialize this equation to the case of matter
perturbations around a black hole, and show that in the WKB approximation, the
wave-functional describes an eternal black hole in equilibrium with a thermal
bath at Hawking temperature.Comment: 13 pages, minor revisions in: (i) para 5 of Introduction, (ii) para
following Eqn. (10). Revised version to appear in Phys. Rev.
Divergence of the Quantum Stress Tensor on the Cauchy Horizon in 2-d Dust Collapse
We prove that the quantum stress tensor for a massless scalar field in two
dimensional non-selfsimilar Tolman Bondi dust collapse and Vaidya radiation
collapse models diverges on the Cauchy horizon, if the latter exists. The two
dimensional model is obtained by suppressing angular co-ordinates in the
corresponding four dimensional spherical model.Comment: 16 pages, no figures, LaTeX fil
A simple derivation of the naked singularity in spherical dust collapse
We describe a simple method of determining whether the singularity that forms
in the spherically symmetric collapse of inhomogeneous dust is naked or
covered. This derivation considerably simplifies the analysis given in the
earlier literature, while giving the same results as have been obtained before.Comment: Latex, 9 page
Can Naked Singularities Yield Gamma Ray Bursts?
Gamma-ray bursts are believed to be the most luminous objects in the
Universe. There has been some suggestion that these arise from quantum
processes around naked singularities. The main problem with this suggestion is
that all known examples of naked singularities are massless and hence there is
effectively no source of energy. It is argued that a globally naked singularity
coupled with quantum processes operating within a distance of the order of
Planck length of the singularity will probably yield energy burst of the order
of M_pc^2\approx2\times 10^{16} ergs, where M_p is the Planck mass.Comment: 4 pages, TeX, no figure
Naked Singularity Explosion
It is known that the gravitational collapse of a dust ball results in naked
singularity formation from an initial density profile which is physically
reasonable. In this paper, we show that explosive radiation is emitted during
the formation process of the naked singularity.Comment: 6 pages, 3 figures, Accepted for Publication in Phys. Rev. D as a
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