Generalized horizon functions for radiating matter

Mahomed, A. B.; Maharaj, S. D.; Narain, R.

doi:10.1140/epjp/s13360-020-00358-z

Cited by 13 publications

(30 citation statements)

References 21 publications

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“…Also, the condition for vanishing shear was made by Charan et al [14], and the shear-free condition has been investigated in different physical scenarios [15][16][17]. Particular models are known which have nonzero shear [18][19][20][21]. Abebe and Maharaj [22] found charged radiating stars using Lie symmetry infinitesimal generators to exactly solve the boundary condition.…”

Section: Introductionmentioning

confidence: 99%

Radiating composite stars with electromagnetic fields

Maharaj

Brassel

2021

Eur. Phys. J. C

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We derive the junction conditions for a general spherically symmetric radiating star with an electromagnetic field across a comoving surface. The interior consists of a charged composite field containing barotropic matter, a null dust and a null string fluid. The exterior atmosphere is described by the generalised Vaidya spacetime. We generate the boundary condition at the stellar surface showing that the pressure is determined by the interior heat flux, anisotropy, null density, charge distribution and the exterior null string density. A new physical feature that arises in our analysis is that the surface pressure depends on the internal charge distribution for generalised Vaidya spacetimes. It is only in the special case of charged Vaidya spacetimes that the matching interior charge distribution is equal to the exterior charge at the surface as measured by an external observer. Previous treatments, for neutral matter and charged matter, arise as special cases in our treatment of composite matter.

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Section: Introductionmentioning

confidence: 99%

Radiating composite stars with electromagnetic fields

Maharaj

Brassel

2021

Eur. Phys. J. C

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“…Observe that exact solutions of (55) and (56), without embedding, have been found by Govender et al [38] and Govender [51] for nonadiabatic spherical collapse. As far as we are aware the only embeddable radiating stellar model known was found by Naidu et al [39] -however this model holds only for the conventional Vaidya model.…”

Section: Radiating Starsmentioning

confidence: 64%

“…The interior matter distribution is heat conducting and the exterior spacetime is given by the conventional Vaidya metric. For comprehensive treatments of recent exact solutions for radiating stellar models see Abebe and Maharaj [52], Mohanlal et al [53] and Mohamed et al [54][55][56]. The generalized Vaidya spacetime may also be used to model a radiating star in general relativity.…”

Section: Radiating Starsmentioning

confidence: 99%

Embedding with Vaidya geometry

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Maharaj

2020

Eur. Phys. J. C

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The Vaidya metric is important in describing the exterior spacetime of a radiating star and for describing astrophysical processes. In this paper we study embedding properties of the generalized Vaidya metric. We had obtained embedding conditions, for embedding into 5-dimensional Euclidean space, by two different methods and solved them in general. As a result we found the form of the mass function which generates a subclass of the generalized Vaidya metric. Our result is purely geometrical and may be applied to any theory of gravity. When we apply Einstein’s equations we find that the embedding generates an equation of state relating the null string density to the null string pressure. The energy conditions lead to particular metrics including the anti/de Sitter spacetimes.

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“…The final remnants of collapsing object are discussed in the paper. Some other authors have also harnessed this concept in context of charge (see [34][35][36]).…”

Section: Introductionmentioning

confidence: 99%

Charged anisotropic spherical collapse with heat flow

2021

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In this article, we study the shear-free gravitational collapse of a charged radiating star. The Einstein field equations of gravitational collapse for the charged stars are known to give rise to a high degree of non-linearity in the ordinary differential equation coming from junction conditions. The attempts to solve it analytically proved to be unfortunate. Numerical methods have been suggested in the past. However, the high degree of non-linearity tends to introduce fluctuations and large round off errors in the numerical calculation. A new ansatz is proposed in the present work to reduce the degree of non-linearity. An ordinary differential equation is derived by satisfying junction conditions, and its numerical solution is demonstrated. Physical quantities associated with the collapse process are plotted to observe the effect of charge on these quantities. It is concluded that the charge can delay the collapse of a star and can even prevent it depending upon the amount of charge. It is also verified that the solution satisfies all the energy conditions.

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Generalized horizon functions for radiating matter

Cited by 13 publications

References 21 publications

Radiating composite stars with electromagnetic fields

Radiating composite stars with electromagnetic fields

Embedding with Vaidya geometry

Charged anisotropic spherical collapse with heat flow

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