Pure Radiation Fields Research Articles

A spherically symmetric gravitational collapse-field with radiation

An interior spherically symmetric solution of Einstein’s field equations corresponding to perfect fluid plus a flowing radiation-field is presented. The physical 3-spacet=constant of our solution is spheroidal. Vaidya’s pure radiation field is taken as the exterior solution. The inward motion of the collapsing boundary surface follows from the equations of fit. An approximation procedure is used to get a generalization of the standard Oppenheimer-Snyder model of collapse with outflow of radiation. One such explicit solution has been given correct to second power of eccentricity of the spheroidal 3-space.

A rotating pure radiation field

Starting with the Kerr solution, we generate an algebraically special pure radiation solution of Einstein's field equations. This solution is axisymmetric, asymptotically flat and regular on the axis. The metric is determined up to a linear second-order ordinary differential equation for which only particular solutions are known. The transformation to Bondi--Sachs coordinates is determined as a power series expansion in terms of the inverse radial coordinate. The relation between our derivation and another approach using Cauchy--Riemann structures is established and the underlying Cauchy--Riemann structure of our solution is given.

NAKED SINGULARITIES AS CANDIDATES FOR GAMMA-RAY BURSTERS

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 less than a critical value. We propose that the gamma-ray bursters (GRBs) are examples of these naked singularity solutions. For illustration, we show that according to solutions involving spherically symmetric collapse of pure radiation field, the energy Eγ and the observed duration Δt0 of a GRB should satisfy, [Formula: see text] being the fraction (10−2 to 10−3) of energy released as gamma rays and the rest possibly as gravitational waves. All the presently observed GRBs satisfy this condition; those satisfying the condition close to equality must necessarily be of cosmological origin with the red-shift factor z not exceeding ~1−10 depending on exact observed flux, red-shift and conversion efficiency of gamma rays. If GRBs are indeed from naked singular regions, they should also be accompanied by a strong burst of gravitational waves which, if detectible, will constitute a basic test for our model.

Group invariant solutions to the Einstein equations with pure radiation fields

The Einstein equations with pure radiation fields and algebraically special metrics are studied. The symmetry group of these equations is systematically exploited to obtain a large number of new explicit solutions. A family of solutions parametrized by a one function of two variables is obtained in the case when the NUT function M vanishes.

Thermoluminescence Dosimetry in Mixed (n,Gamma) Radiation Fields Using Glow Curve Superposition

A new method (glow curve superposition) is introduced to measure absorbed doses in mixed (n,γ) radiation fields using thermoluminescence dosemeters. The new method is closely related to the so-called two peak method. The basic idea of the method is that the glow curve of a TL material irradiated in a mixed (n,γ) radiation field is a superposition of two glow curves obtained in pure photon and neutron radiation fields. The glow curve superposition method appears to be more accurate than the two peak method when one of the components of the mixed field strongly dominates.

Spherically symmetric radiating solution with heat flow in general relativity

A model describing a collapsing sphere with radial heat flow is studied. Vaidya’s pure radiation field is taken as the exterior solution. The motion of the boundary surface follows from the matching conditions. In the remote part, the evolution starts with the interior and exterior Schwarzschild solution.

TRANSPARENCY OF DOMAIN WALLS TO ELECTROMAGNETIC AND NEUTRINO WAVES: AN EXACT SOLUTION

An exact solution of the Einstein-Maxwell-Weyl equations is given, which represents a planar domain wall accompanied by electromagnetic and neutrino waves. It is found that the wall is entirely transparent to these two pure radiation fields, and that the evolution of the wall is not affected by the presence of them.

Algebraically special solutions of the Einstein equations with pure radiation fields

The Einstein equations Rmu v= Phi kmu kv, kmu being tangent to a twisting shear-free congruence of null geodesics, are formulated as equations in a three-dimensional Cauchy-Riemann space. If the NUT parameter M vanishes and the Cauchy-Riemann space is a hypersurface in C2 then the equations reduce to a single linear second-order equation. New gravitational solutions are found for the case of the Robinson congruence.

A class of exact solutions of the Einstein–Dirac equations

All exact solutions of the Einstein–Dirac field equations are given that satisfy the energy conditions and for which the spinor components of the Dirac bispinor are aligned but have different amplitude. They are all pure radiation fields of Kundt’s class.

Aligned twisting pure radiation fields of Petrov type D do not exist

The recent proof by Debever, Van den Bergh and Leroy (1989) that diverging null Einstein-Maxwell fields of Petrov type D are necessarily non-twisting, can simply be extended to aligned pure radiation fields.

Neutrino fields of embedding class one

Neutrino fields obeying the dominant energy condition can be of embedding class one only if they are pure radiation fields of Petrov type N.

Petrov type D pure radiation fields of Kundt's class

It is shown that Petrov type D pure radiation fields of Kundt's class can be generated from Kinnersley's B metric. These fields do not admit a null electromagnetic, neutrino or massless scalar field source.

Homogeneous and conformally Ricci flat pure radiation fields

Some unsolved problems concerning pure radiation fields in general relativity are studied. The general solutions for homogeneous and for conformally Ricci flat metrics are given. They are all of Petrov type N or O, and contain a hitherto unidentified conformally flat metric. Non-aligned Petrov type III pure radiation metrics are shown not to exist.

Radiating Kerr particle in Einstein universe

A generalized Kerr-NUT type metric is considered in connection with Einstein field equations corresponding to perfect fluid plus a pure radiation field. A general scheme for obtaining the exact solutions of these field equations is developed. Two physically meaningful particular cases are investigated in detail. One gives the field of a radiating Kerr particle embedded in the Einstein universe. The other solution may probably represent a deSitter-like universe pervaded by a pure radiation field.

A Kerr-like radiating metric in the expanding universe

Using the method of differential forms a Kerr-like metric is derived as an exact solution of Einstein’s field equations corresponding to a perfect fluid distribution plus a pure radiation field. The solution is interpreted as a Kerr-like radiating metric in the cosmological background of an expanding universe. The radiating Kerr metric and the radiating associated Kerr metric are derived as particular cases. The details of the solution are also discussed.

Radiating Demianski-type metrics and the Einstein-Maxwell fields

AbstractA Demianski-type metric is investigated in connection with the Einstein-Maxwell fields. Using complex vectorial formalism, some exact solutions of Einstein-Maxwell field equations for source-free electromagnetic fields plus pure radiation fields are obtained. The radiating Demianski solution, the Debney-Kerr-Schild solution and the Brill solution are derived as particular cases.

On ?Radiating Vaidya metric imbedded in deSitter space?

Mallett has generalized the Vaidya metric as well as the deSitter metric to obtain what he called the “Vaidya-Schwarzschild-deSitter metric” and has obtained the condition under which this metric represents a pure radiation field. The present note obtains the complete first integral of that equation as well as well as some particular solutions.

Gravitational fields with space-times of Bianchi type IX

Spatially homogeneous space-times of Bianchi type IX are considered. A general scheme for the derivation of exact solutions of Einstein’s equations corresponding to perfect fluid plus pure radiation fields is outlined. Some simple rotating Bianchi type IX cosmological models are presented. The details of these solutions are also discussed.

Another approach to quantum electrodynamics

In order to investigate the Gupta-Bleuler theory of the quantum electrodynamics from another point of view, one method is given which transforms the conventional metric to a new tensor byR-matrix and allows a canonical formalism that avoids the difficulty of making the momentum of the scalar photon identically vanish. As a consequence a general eigenstate of the pure radiation field is given in contrast to Gupta-Bleuler's. The expectation value of the subsidiary condition for the ghost state, corresponding to the Lorentz condition in the classical theory, vanishes.

Field theory, curdling, limit cycles, and cellular automata

It is suggested that the process of curdling is an important question for the science of fractals. A field equation which displays nucleation (curdling) of particles out of a pure radiation field is discussed. The particle formation arises naturally from the nonlinear character of the equation rather than from imposed quantization conditions. The relativistically invariant equation is $$div(\rho ^\mu (r,t,\Omega _1 )) = \int {[\rho _\mu (r,t,\Omega ),\rho ^\mu (r,t,\Omega _2 )]d} \Omega _2 $$ where ¦, ¦ denotes commutator.ρμ(r,t,Ω) is both a 4-vector and a 2×2 matrix. It represents substance atr, t traveling with the velocity of light in direction Ω. A unique feature is that the scattering ofρ(Ω1) byρ(Ω2) as determined by the right-hand side of the above equation results in fields that persist at a given place even thoughρ itself represents substance traveling always at the speed of light. Explicit solutions are given for the case of one dimension. Fields representing particles are obtained and shown to have specially oscillatory structure with incipient fractal character.