Relativistic model of radiating massive fluid sphere

Pant, Neeraj; Mehta, Rama Nand; Tewari, B. C.

doi:10.1007/s10509-010-0320-3

Cited by 12 publications

(9 citation statements)

References 29 publications

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“…Such radiation pressure supported quasi-static objects are just the extreme general relativistic versions (z 1) of quasi-Newtonian (z 1) radiation pressure supported objects conceived by Hoyle and Fowler long back (Fowler 1966;Hoyle and Fowler 1963). Indeed, it is known that GR may allow extremely compact radiation dominated massive spheres too and which can be viewed as the central engine of Active Galactic Nuclei (Pant et al 2010;Pant and Tewari 2010;Tewari 2006). In particular, there are specific model for formation of such radiation supported objects in horizonless GR collapse (Pant and Tewari 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, it is known that GR may allow extremely compact radiation dominated massive spheres too and which can be viewed as the central engine of Active Galactic Nuclei (Pant et al 2010;Pant and Tewari 2010;Tewari 2006). In particular, there are specific model for formation of such radiation supported objects in horizonless GR collapse (Pant and Tewari 2010).…”

Section: Discussionmentioning

confidence: 99%

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The fallacy of Oppenheimer Snyder collapse: no general relativistic collapse at all, no black hole, no physical singularity

Mitra

2010

Astrophys Space Sci

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By applying Birkhoff's theorem to the problem of the general relativistic collapse of a uniform density dust, we directly show that the density of the dust ρ = 0 even when its proper number density n would be assumed to be finite! The physical reason behind this exact result can be traced back to the observation of Arnowitt et al. (Phys. Rev. Lett. 4: 375, 1960) that the gravitational mass of a neutral point particle is zero: m = 0. And since, a dust is a mere collection of neutral point particles, unlike a continuous hydrodynamic fluid, its density ρ = mn = 0. It is nonetheless found that for k = −1, a homogeneous dust can collapse and expand special relativistically in the fashion of a Milne universe. Thus, in reality, general relativistic homogeneous dust collapse does not lead to the formation of any black hole in conformity of many previous studies (Logunov et al.this result is in agreement with the intuition of Oppenheimer and Snyder (Phys. Rev. 56: 456, 1939) too:"Physically such a singularity would mean that the expressions used for the energy-momentum tensor does not take into account some essential physical fact which would really smooth the singularity out. Further, a star in its early stages of development would not possess a singular density or pressure, it is impossible for a singularity to develop in a finite time."

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The fallacy of Oppenheimer Snyder collapse: no general relativistic collapse at all, no black hole, no physical singularity

Mitra

2010

Astrophys Space Sci

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“…There are innumerable studies on such physical gravitational collapse; in particular, an interested reader may look into (Herrera and Santos 2004;Herrera et al 2006aHerrera et al , 2006bHerrera et al , 2009Kramer 1992;Pant et al 2010;Pant and Tewari 2011;Chan 2008, 2010). Such physical studies may be also extended for a quasi-spherical case and in arbitrary higher dimensions too (Debnath et al 2005).…”

Section: Collapsing Homogeneous Sphere With a Boundarymentioning

confidence: 99%

The matter in the Big-Bang model is dust and not any arbitrary perfect fluid!

Mitra

2011

Astrophys Space Sci

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We consider a spherically symmetric general relativistic perfect fluid in its comoving frame. It is found that, by integrating the local energy momentum conservation equation, a general form of g 00 can be obtained. During this study, we get a cue that an adiabatically evolving uniform density isolated sphere having ρ(r, t) = ρ 0 (t), should comprise "dust" having p 0 (t) = 0; as recently suggested by Durgapal and Fuloria (J. Mod. Phys. 1:143, 2010) In fact, we offer here an independent proof to this effect. But much more importantly, we find that for the homogeneous and isotropic Friedmann-Robertson-Walker (FRW) metric having p(r, t) = p 0 (t) and ρ(r, t) = ρ 0 (t), g 00 = e −2p 0 /(p 0 +ρ 0 ) . But in general relativity (GR), one can choose an arbitrary t → t * = f (t) without any loss of generality, and thus set g 00 (t * ) = 1. And since pressure is a scalar, this implies that p 0 (t * ) = p 0 (t) = 0 in the Big-Bang model based on the FRW metric. This result gets confirmed by the fact the homogeneous dust metric having p(r, t) = p 0 (t) = 0 and ρ(r, t) = ρ 0 (t) and the FRW metric are exactly identical. In other words, both the cases correspond to the same Einstein tensor G a b because they intrinsically have the same energy momentum tensor T a b = diag[ρ 0 (t), 0, 0, 0].

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“…In the absence of a trapped surface or EH, such objects must keep on radiating and contracting even if at infinitesimally slow rate. In fact there are several GTR special solutions for physical gravitational collapse which suggest that effect of radiation pressure and dissipation may cause formation of hot radiating ultra-compact objects rather that any BH or naked singularity [34,35]. Radiation pressure apart, generation of tangential pressure too can arrest the continued collapse.…”

Section: Gravitational Collapsementioning

confidence: 99%