Constraints on exotic matter needed for an emergent universe

Paul, Bikash Chandra; Thakur, P.; Ghose, Subrata

doi:10.1111/j.1365-2966.2010.16909.x

Cited by 48 publications

(36 citation statements)

References 25 publications

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“…Therefore we turn our attention to the case when β ≈ 0. This situation studied by Paul et al [13]. Note that we analyze the integration only for χ in Eq.…”

Section: Closed and Open Emu With Three Chiral Cosmological Fieldsmentioning

confidence: 98%

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Emergent universe supported by chiral cosmological fields in 5D Einstein-Gauss-Bonnet gravity

et al. 2014

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We propose the application of the chiral cosmological model (CCM) for the Einstein-Gauss-Bonnet (EGB) theory of gravitation with the aim of finding new models of the Emergent Universe (EmU) scenario. We analysed the EmU supported by two chiral cosmological fields for a spatially flat universe, while we have used three chiral fields when we investigated open and closed universes. To prove the validity of the EmU scenario we fixed the scale factor and found the exact solution by decomposition of EGB equations and solving the chiral field dynamics equation. To this end, we suggested the decomposition of the EGB equations in such a way that the first chiral field is responsible for the Einstein part of the model, while the second field, together with kinetic interaction term, is connected with the Gauss-Bonnet part of the theory. We proved that both fields are phantom ones under this decomposition, and that the model has a solution if the kinetic interaction between the fields equals a constant. We have presented the exact solution in terms of cosmic time. This was done for a spatially flat universe. In the case of open and closed universes we introduced the third chiral field (canonical for closed and phantom for open universe) which is responsible for the EGB and curvature parts. The solution of the third field equation is obtained in quadratures. Thus we have proved that the CCM is able to support EmU scenario in EGB gravity for spatially flat, open and closed universes.

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“…Therefore we turn our attention to the case when β ≈ 0. This situation studied by Paul et al [13]. Note that we analyze the integration only for χ in Eq.…”

Section: Closed and Open Emu With Three Chiral Cosmological Fieldsmentioning

confidence: 98%

“…With this we can set h 22 = 1 without loss of generality, and look for the solution of the second field equation (13). To this end we will multiply the Eq.…”

Section: The Solution Of Dynamic Equationsmentioning

confidence: 99%

Emergent universe supported by chiral cosmological fields in 5D Einstein-Gauss-Bonnet gravity

et al. 2014

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“…This model (2.1) can produce a emergent universe without the time singularity [43][44][45][46]. But in this paper, we will take this RMCG fluid as the dark components in our Universe.…”

Section: Dark Models In Rmcg Cosmologymentioning

confidence: 99%

Reduced modified Chaplygin gas cosmology

Geng

et al. 2015

J. High Energ. Phys.

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Abstract:In this paper, we study cosmologies containing the reduced modified Chaplygin gas (RMCG) fluid which is reduced from the modified Chaplygin gas p = Aρ − Bρ −α for the value of α = −1/2. In this special case, dark cosmological models can be realized for different values of model parameter A. We investigate the viabilities of these dark cosmological models by discussing the evolutions of cosmological quantities and using the currently available cosmic observations. It is shown that the special RMCG model (A = 0 or A = 1) which unifies the dark matter and dark energy should be abandoned. For A = 1/3, RMCG which unifies the dark energy and dark radiation is the favorite model according to the objective Akaike information criteria. In the case of A < 0, RMCG can achieve the features of the dynamical quintessence and phantom models, where the evolution of the universe is not sensitive to the variation of model parameters.

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“…In this section, we perform a detailed observational data analysis [31,32,33,34,35] using Stern data. We also study the model under Stern+BAO and Stern+BAO+CMB joint analysis.…”

Section: Observational Constraints On Eos Parametersmentioning

confidence: 99%

Observational Data Fitting to Constrain Variable Modified Chaplygin Gas in the Background of Horava-Lifshitz Gravity

Ranjit¹,

Rudra²

2015

Int J Theor Phys

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FRW universe in Horava-Lifshitz (HL) gravity model filled with a combination of dark matter and dark energy in the form of variable modified Chaplygin gas (VMCG) is considered. The permitted values of the VMCG parameters are determined by the recent astrophysical and cosmological observational data. Here we present the Hubble parameter in terms of the observable parameters Ω dm0 , Ω vmcg0 , H 0 , redshift z and other parameters like α, A, γ and n. From Stern data set (12 points), we have obtained the bounds of the arbitrary parameters by minimizing the χ 2 test. The best-fit values of the parameters are obtained by 66%, 90% and 99% confidence levels. Next due to joint analysis with BAO and CMB observations, we have also obtained the bounds of the parameters (A, γ) by fixing some other parameters α and n. The best fit value of distance modulus µ(z) is obtained for the VMCG model in HL gravity, and it is concluded that our model is perfectly consistent with the union2 sample data.Pacs no : 04.60. Pp, 98.80.Qc,

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Constraints on exotic matter needed for an emergent universe

Cited by 48 publications

References 25 publications

Emergent universe supported by chiral cosmological fields in 5D Einstein-Gauss-Bonnet gravity

Emergent universe supported by chiral cosmological fields in 5D Einstein-Gauss-Bonnet gravity

Reduced modified Chaplygin gas cosmology

Observational Data Fitting to Constrain Variable Modified Chaplygin Gas in the Background of Horava-Lifshitz Gravity

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