Electromagnetic Fields of Slowly Rotating Magnetized Gravastars

Turimov, Bobur; Ahmedov, Bobomurat; Abdujabbarov, Ahmadjon

doi:10.1142/s0217732309030497

Cited by 61 publications

(30 citation statements)

References 13 publications

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“…However, these works are mainly carried out by several authors in the framework of Einstein's general relativity [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Though it is well known that Einstein's general relativity is a unique tool for uncovering many hidden mysteries of Nature, yet some observational evidences of the accelerating universe along with the existence of dark matter has imposed a theoretical challenge to this theory [20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Gravastars in f(R,T) gravity

Das¹,

Ghosh²,

Guha³

et al. 2017

Phys. Rev. D

191

118

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We propose a unique stellar model under the f (R, T ) gravity by using the conjecture of MazurMottola [P. Mazur and E. Mottola, Report number: LA-UR-01-5067., P. Mazur and E. Mottola, Proc. Natl. Acad. Sci. USA 101, 9545 (2004).] which is known as gravastar and a viable alternative to the black hole as available in literature. This gravastar is described by the three different regions, viz., (I) Interior core region, (II) Intermediate thin shell, and (III) Exterior spherical region. The pressure within the interior region is equal to the constant negative matter density which provides a repulsive force over the thin spherical shell. This thin shell is assumed to be formed by a fluid of ultrarelativistic plasma and the pressure, which is directly proportional to the matter-energy density according to Zel'dovich's conjecture of stiff fluid [Y.B. Zel'dovich, Mon. Not. R. Astron. Soc. 160, 1 (1972).], does counterbalance the repulsive force exerted by the interior core region. The exterior spherical region is completely vacuum and assumed to be de Sitter spacetime which can be described by the Schwarzschild solution. Under this specification we find out a set of exact and singularity-free solution of the gravastar which presents several other physically valid features within the framework of alternative gravity.

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Section: Introductionmentioning

confidence: 99%

Gravastars in f(R,T) gravity

Das¹,

Ghosh²,

Guha³

et al. 2017

Phys. Rev. D

191

118

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“…Considerable effort has been dedicated to study gravastars, for instance exploring different possibilities for its structure [2,3], generalising the solution [4][5][6] and investigating possible observational signatures [7][8][9]. As alternatives almost indistinguishable from a black hole in terms of electromagnetic radiation, gravastars have attracted the attention of those who wished for a spacetime solution without the issues brought by the existence of singularities and event horizons.…”

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confidence: 99%

Did GW150914 produce a rotating gravastar?

2016

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The interferometric LIGO detectors have recently measured the first direct gravitational-wave signal from what has been interpreted as the inspiral, merger and ringdown of a binary system of black holes. The signalto-noise ratio of the measured signal is large enough to leave little doubt that it does refer to the inspiral of two massive and ultracompact objects, whose merger yields a rotating black hole. Yet, the quality of the data is such that some room is left for alternative interpretations that do not involve black holes, but other objects that, within classical general relativity, can be equally massive and compact, namely, gravastars. We here consider the hypothesis that the merging objects were indeed gravastars and explore whether the merged object could therefore be not a black hole but a rotating gravastar. After comparing the real and imaginary parts of the ringdown signal of GW150914 with the corresponding quantities for a variety of gravastars, and notwithstanding the very limited knowledge of the perturbative response of rotating gravastars, we conclude it is not possible to model the measured ringdown of GW150914 as due to a rotating gravastar.PACS numbers: 04.25. Dm, 04.25.dk, 04.30.Db, 04.40.Dg, 95.30.Lz, 95.30.Sf, 97.60.Jd Introduction. Gravastars were proposed in 2004 by Mazur and Mottola [1] as an ingenious alternative to the end state of stellar evolution for very massive stars, that is, as an alternative to black holes. The name gravastar comes from "gravitational vacuum condensate star" and it was proposed to be almost as compact as a black hole, but without an event horizon or a central singularity. This object would be formed as gravitational collapse brought the stellar radius very close to its Schwarzschild radius and as a phase transition would form a de Sitter core. This "repulsive" core stabilises the collapse, while the baryonic mass ends as a shell of stiff matter surrounding the core. Despite their uncertain and rather exotic origin, gravastars are perfectly acceptable solutions of the Einstein equations within classical general relativity.Considerable effort has been dedicated to study gravastars, for instance exploring different possibilities for its structure [2,3], generalising the solution [4-6] and investigating possible observational signatures [7][8][9]. As alternatives almost indistinguishable from a black hole in terms of electromagnetic radiation, gravastars have attracted the attention of those who wished for a spacetime solution without the issues brought by the existence of singularities and event horizons. Work was also done in order to assess its viability, in particular looking for instabilities in the solutions. Hence, there have been studies on the stability against radial oscillations [2,10] and axial and polar gravitational perturbations [11][12][13]. For slowly rotating gravastars, scalar perturbations in the context of the ergoregion instability were also studied [14,15]. None of these works has pointed out to a response that would allow one to discard...

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“…These types of gravitationally vacuum stars were termed as gravastars. Thereafter several scientists have been studied these models under different viewpoints and have opened up a new field of research as an alternative to Black Holes [3,4,5,6,7,8,9,10,11,12,13,14,15].…”

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confidence: 99%

Charged gravastars in higher dimensions

et al. 2017

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We explore possibility to find out a new model of gravastars in the extended $D$-dimensional Einstein-Maxwell spacetime. The class of solutions as obtained by Mazur and Mottola of a neutral gravastar \cite{Mazur2001,Mazur2004} have been observed as an alternative to $D$-dimensional versions of the Schwarzschild-Tangherlini black hole. To tackle the spherical system in a convenient way we have configured that the gravastar consists of three distinct regions with different equations of state as follows: [I] Interior region $0 \leq r < r_1$,$\rho = -p$, [II] Thin shell region $r_1 \leq r < r_2$,$\rho = p$, and [III] Exterior region $r_2 < r$,$\rho = p =0$. The outer region of this gravastar model therefore corresponds to a higher dimensional Reissner-Nordstr{\"o}m black hole. In connection to this junction conditions are provided and therefore we have formulated mass and the related Equation of State of the gravastar. It has been shown that the model satisfies all the requirements of the physical features. However, overall observational survey of the results also provide probable indication of non-applicability of higher dimensional approach for construction of a gravastar with or without charge from an ordinary $4$-dimensional seed as far as physical ground is concerned.Comment: 17 pages, 3 figure

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Electromagnetic Fields of Slowly Rotating Magnetized Gravastars

Cited by 61 publications

References 13 publications

Gravastars in f(R,T) gravity

Gravastars in f(R,T) gravity

Did GW150914 produce a rotating gravastar?

Charged gravastars in higher dimensions

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