Radiation and string atmosphere for relativistic stars

Glass, E. N.; Krisch, J. P.

doi:10.1103/physrevd.57.r5945

Cited by 57 publications

(95 citation statements)

References 11 publications

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“…Depending on the initial distribution of density and velocity and on the constitutive nature of the collapsing matter, either a black hole or a naked singularity is formed. The values of the parameters in the solution (22) and (24) determine which of these possibilities occurs. The solution describing the collapse of both the Hagedorn and Zeldovich matter is asymptotically flat, but this condition does not play any significant role in the formation of the naked singularity.…”

Section: Collapsing Hagedorn Matter-a Possible Source Of Gamma-raymentioning

confidence: 99%

“…In the framework of the same approach a large class of solutions, including Type II fluids, and which includes most of the known solutions of the Einstein field equations, has been derived, in four dimensions by Wang and Wu [22], and in N ≥ 4 dimensions by Villas da Rocha [23]. The Vaidya radiating metric has been extended to include both a radiation field and a string fluid by Glass and Krisch [24], [25] and by Govinder and Govender [26].…”

Section: Introductionmentioning

confidence: 99%

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Gravitational collapse of a Hagedorn fluid in Vaidya geometry

Harkó

2003

Phys. Rev. D

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The gravitational collapse of a high-density null charged matter fluid, satisfying the Hagedorn equation of state, is considered in the framework of the Vaidya geometry. The general solution of the gravitational field equations can be obtained in an exact parametric form. The conditions for the formation of a naked singularity, as a result of the collapse of the compact object, are also investigated. For an appropriate choice of the arbitrary integration functions the null radial outgoing geodesic, originating from the shell focussing central singularity, admits one or more positive roots. Hence a collapsing Hagedorn fluid could end either as a black hole, or as a naked singularity. A possible astrophysical application of the model, to describe the energy source of gamma-ray bursts, is also considered.

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Section: Collapsing Hagedorn Matter-a Possible Source Of Gamma-raymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

Harkó

2003

Phys. Rev. D

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“…Here, we are interested in the Vaidyalike radiating black hole solution for a cloud of strings in Lovelock gravity. Hence the energy momentum tensor we consider includes both a null dust and a string fluid, i.e., a two-fluid description of radial strings and outward flowing short-wavelength photons that is null dust [21]. In order to see the two-fluid description we use the above timelike unit velocity vectorv µ and unit spacelike vectorŝ r µ ,θ µ ,φ µ (θn) such that…”

Section: The String-cloud Modelmentioning

confidence: 99%

“…Initially m(v, r) = m 0 provides the vacuum Schwarzschild solution in the region r > 2m 0 > 0. The metric in Ndimensional spherically symmetric spacetime is given in terms of the advanced time coordinate v. Using the Newman-Penrose null tetrad formalism the principal null vectors l µ , n µ are of the form [21] …”

Section: The String-cloud Modelmentioning

confidence: 99%

“…It is possible to model the radiating star by matching it to the exterior Vaidya spacetime (see [16,17] for reviews on the Vaidya solution and [18] for the higher-dimensional version). On the other hand relativistic strings can be used to describe the large scale anisotropy of the universe [19], and also to describe extended objects in general relativity [20], e.g., to model stars [21], and black holes [11].…”

Section: Introductionmentioning

confidence: 99%

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Cloud of strings for radiating black holes in Lovelock gravity

Ghosh

Maharaj

2014

Phys. Rev. D

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We present exact spherically symmetric null dust solutions in the third order Lovelock gravity with a string cloud background in arbitrary N dimensions,. This represents radiating black holes and generalizes the well known Vaidya solution to Lovelock gravity with a string cloud in the background. We also discuss the energy conditions and horizon structures, and explicitly bring out the effect of the string clouds on the horizon structure of black hole solutions for the higher dimensional general relativity and Einstein-Gauss-Bonnet theories. It turns out that the presence of the coupling constant of the Gauss-Bonnet terms and/or background string clouds completely changes the structure of the horizon and this may lead to a naked singularity. We recover known spherically symmetric radiating models as well as static black holes in the appropriate limits.

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Rotating metrics admitting non-perfect fluids

Ibohal

2005

Gen Relativ Gravit

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In this paper an application of Newman-Janis algorithm in spherically symmetric metrics with the functions M (u, r) and e(u, r) has been discussed. After the transformation of the metric via this algorithm, these two functions M (u, r) and e(u, r) will be transformed to depend on the three variables u, r, θ. With these functions of three variables, all the Newman-Penrose (NP) spin coefficients, the Ricci as well as the Weyl scalars have been calculated from the Cartan's structure equations. Using these NP quantities, we first give examples of rotating solutions of Einstein's field equations like Kerr-Newman, rotating Vaidya solution and rotating Vaidya-Bonnor solution. It is found that the technique developed by Wang and Wu can be used to give further examples of embedded rotating solutions, that the rotating Kerr-Newman solution can be combined smoothly with the rotating Vaidya solution to derive the Kerr-Newman-Vaidya solution, and similarly, Kerr-Newman-Vaidya-Bonnor solution of the field equations. It has also been shown that the embedded universes like Kerr-Newman de Sitter, rotating Vaidya-Bonnor-de Sitter, Kerr-Newman-Vaidya-de Sitter can be derived from the general solutions with Wang-Wu function. All rotating embedded solutions derived here can be written in Kerr-Schild forms, showing the extension of Xanthopoulos's theorem. It is also found that all the rotating solutions admit non-perfect fluids.

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Radiation and string atmosphere for relativistic stars

Abstract: We extend the Vaidya radiating metric to include both a radiation field and a string fluid. Assuming diffusive transport for the string fluid, we find new analytic solutions of Einstein's field equations. Our new solutions represent an extention of Xanthopoulos superposition.

Cited by 57 publications

References 11 publications

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

Cloud of strings for radiating black holes in Lovelock gravity

Rotating metrics admitting non-perfect fluids

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