Modified Chaplygin Traversable Wormholes

Chakraborty, Subenoy; Bandyopadhyay, Tanwi

doi:10.1142/s0218271809014480

Cited by 31 publications

(23 citation statements)

References 43 publications

(39 reference statements)

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“…Dotti et al [51] considered higher dimensional gravity and studied wormhole solutions in vacuum. Spherically symmetric traversable wormholes have also been studied using modified Chaplygin gas in [52][53][54]. Lobo and Oliveira [55] developed traversable wormhole structures in modified f (R) gravity.…”

Section: Introductionmentioning

confidence: 99%

Traversable wormholes and energy conditions with two different shape functions in f(R) gravity

Godani

Samanta

2019

Int. J. Mod. Phys. D

110

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Traversable wormholes, tunnel like structures introduced by Morris & Thorne [1], have a significant role in connection of two different space-times or two different parts of the same space-time. The characteristics of these wormholes depend upon the redshift and shape functions which are defined in terms of radial coordinate. In literature, several shape functions are defined and wormholes are studied in f (R) gravity with respect to these shape functions [55,57,60]. In this paper, two shape functions (i) b(r) = r 0 log(r + 1) log(r 0 + 1) and (ii) b(r) = r 0 ( r r 0 ) γ , 0 < γ < 1 are considered. The first shape function is newly defined, however the second one is collected from the literature [77]. The wormholes are investigated for each type of shape function in f (R) gravity with f (R) = R + αR m − βR −n , where m, n, α, and β are real constants. Varying parameters α or β, f (R) model is studied in five subcases for each type of shape function. In each case, the energy density, radial & tangential pressures, energy conditions that include null energy condition, weak energy condition, strong energy condition & dominated energy condition, and anisotropic parameter are computed. The energy density is found to be positive and all energy conditions are obtained to be violated which supports the existence of wormholes. Also, the equation of state parameter is obtained to possess values less than -1, that shows the presence of the phantom fluid and leads towards the expansion of the universe.

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Section: Introductionmentioning

confidence: 99%

Traversable wormholes and energy conditions with two different shape functions in f(R) gravity

Godani

Samanta

2019

Int. J. Mod. Phys. D

110

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“…• If the free function is b(r) [14,18], then from (2) we derive µ(r) and from (12), µ(β, ζ). If moreover b(r) is invertible to get r(b), then from (2), one gets µ(r) = µ(b) = µ(β).…”

Section: A Dynamical Systemmentioning

confidence: 99%

“…from which we get µ(β, ζ) with (9) and (12). If moreover r(P ) can be calculated, one derives ζ(β, θ) from (18) and thus µ(β, θ) from µ(β, ζ).…”

Section: A Dynamical Systemmentioning

confidence: 99%

“…The weak energy condition is thus violated that explains the presence of a throat in (β, θ) = (0, 1). Then using (18), it comes that µ = (n − arctanh θ)(−1 + arctanh β + 2 arctanh β arctanh θ) arctanh θ µ is independent on ζ and the dynamical system thus reduces to two differential equations for β ′ and θ ′ . The flaringout condition β ′ (r 0 ) > 0 implies p 0 r 2−n 0 > −1.…”

Section: A Toy Model Of Asymptotically Flat Wormhole On Both Side mentioning

confidence: 99%

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Phase space of static wormholes sustained by an isotropic perfect fluid

Fay

2019

Gen Relativ Gravit

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A phase space is built that allows to study, classify and compare easily large classes of static spherically symmetric wormholes solutions, sustained by an isotropic perfect fluid in General Relativity. We determine the possible locations of equilibrium points, throats and curvature singularities in this phase space. Throats locations show that the spatial variation of the gravitational redshift at the throat of a static spherically symmetric wormhole sustained by an isotropic perfect fluid is always diverging, generalising the result that there is no such wormhole with zero-tidal force. Several specific static spherically symmetric wormholes models are studied. A vanishing density model leads to an exact solution of the field equation allowing to test our dynamical system formalism. It also shows how to extend it to the description of static black holes. Hence, the trajectory of the Schwarzschild black hole is determined. The static spherically symmetric wormhole solutions of several usual isotropic dark energy (generalised Chaplygin gas, constant, linear and Chevallier-Polarski-Linder equations of state) and dark matter (Navarro-Frenk-White profile) models are considered. They show various behaviours far from the throat: singularities, spatial flatness, cyclic behaviours, etc. None of them is asymptotically Minkowski flat. This discards the natural formation of static spherically symmetric and isotropic wormholes from these dark fluids. Last we consider a toy model of an asymptotically Minkowski flat wormhole that is a counterexample to a recent theorem claiming that a static wormhole sustained by an isotropic fluid cannot be asymptotically flat on both sides of its throat.PACS numbers: 95.30.Sf, 98.80.Jk

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“…In this article, we have considered another DE model known as the Modified Chaplygin Gas(MCG). It has its origin from the brane world scenario [24] and its EoS is given as:…”

Section: Introductionmentioning

confidence: 99%

Search for missing links between two extreme wind speed profiles: dark energy accretion and adiabatic fluid accretion

Roy

Biswas

2020

Eur. Phys. J. C

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In the recent past, progress in accretion studies onto general relativistically gravitating central objects viz. a Schwarzschild singularity reveals that the accretion flow should be transonic. Regarding such cases, radial inward speed gradient might be written as a numerator over denominator form among which the denominator vanishes somewhere in between infinite distance to the event horizon of the attractor. For sustainability of a physical solution, the numerator should also have to be equal to zero at the same radial distance where the denominator does vanish. From this point, using L'Hospital's rule, we obtain a second degree first order differential equation of radial inward speed. Hence, using the initial conditions at the said radial distance, we obtain two branches of flow by the virtue of two first order differential equations. These branches are named as accretion and wind. For adiabatic accretion case, the slope of the wind curve in speed vs radial distance plane is formed to be more or less parallel to the radial distance axis as we move far from the central object. For dark energy accretion, alignment of this curve is parallel to the radial velocity axis. Here we face a question why there is no fluid speed profile in between these two extremities. While searching for the reasons, we follow that dark energy, if treated as an accreting object, should stay around the central compact star and hence will contaminate the metric which properties the compact star. In this research work, we have proposed a model with a rotating black hole embedded in quintessence where quintessence equation of state and spin parameter of the black hole are together working as the regulatory factors of the model. The resulting accretion and wind curves are studied. The Effect of negative pressure of dark energy is found to get catalyzed by the entry of the spin of the black hole. We tally our results with observations of accretion or outflow phenomenon near to different quasars.

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Modified Chaplygin Traversable Wormholes

Cited by 31 publications

References 43 publications

Traversable wormholes and energy conditions with two different shape functions in f(R) gravity

Traversable wormholes and energy conditions with two different shape functions in f(R) gravity

Phase space of static wormholes sustained by an isotropic perfect fluid

Search for missing links between two extreme wind speed profiles: dark energy accretion and adiabatic fluid accretion

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