Emergent universe with exotic matter

Mukherjee, S.; Paul, Bikash Chandra; Dadhich, Naresh; Maharaj, S. D.; Беешам, Ароонкумар

doi:10.1088/0264-9381/23/23/020

Cited by 187 publications

(276 citation statements)

References 22 publications

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“…This theorem was developed in 2003 by Arvind Borde, Alan Guth and Alex Vilenkin [8].Vilenkin's arguments demonstrate that null and time-like geodesics are generally incomplete in inflationary models, regardless of whether energy conditions are maintained, provided that the average expansion condition (H > 0) is maintained throughout of these geodesics directed towards the past. The search for cosmological models without initial singularities has led to the development of emergent universes models (UE) [9,10,11,12,13,14,15,16]. However, most simple models developed in a context of General Relativity suffer from instabilities, associated with the instability of Einstein's static universe [17].…”

Section: Introductionmentioning

confidence: 99%

Tunneling and the Emergent Universe scheme in a JBD Theory

Cossio

Labraña

2018

J. Phys.: Conf. Ser.

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Abstract.In this work it is proposed an alternative scheme for an Emergent Universe scenario in the context of a Jordan-Brans-Dicke theory, where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum.In particular, in this work we study the stability of the static universe, under the aforementioned characteristics, and the probability of creating a true vacuum bubble. It is shown that in this model, unlike what happens in previous works, the static universe is stable under small classical perturbations.

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Section: Introductionmentioning

confidence: 99%

Tunneling and the Emergent Universe scheme in a JBD Theory

Cossio

Labraña

2018

J. Phys.: Conf. Ser.

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“…In the literature the late accelerating phase of the universe is obtained with exotic matter or with a modification of the Einstein gravity. A non-linear equation of state is also considered in the literature to construct cosmologies [13], emergent universe model is one such model. The Emergent universe (EU) model obtained by Mukherjee et al in the flat universe permits an accelerating phase.…”

Section: Introductionmentioning

confidence: 99%

“…EU scenario has been explored with quintom matter [16] and further investigated the realization of the scenario with a non-conventional fermion field to obtain a scale invariant perturbation [17]. It has been shown that the EU scenario can be implemented successfully in the framework of general relativity [13] in addition to Gauss-Bonnet gravity [18]. The modified Gauss-Bonnet gravity as gravitational alternative for dark energy is however considered by Nojiri and Oddintsov [19].…”

Section: Introductionmentioning

confidence: 99%

“…A number of cosmological models are obtained with different cosmological fluids and fields [14,[23][24][25][26] where initial singularity problem is addressed. Mukherjee et al [13] obtained an emergent universe model in the framework of GTR with a polytropic equation of state (EoS) given by…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [13], it is shown that for discrete set of values of A namely, A(= 0, −1/3, 1/3, 1), one obtains universe with a mixture of three different kinds of cosmic fluids. The dark energy is one of the prime constituents of the mixture.…”

Section: Introductionmentioning

confidence: 99%

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Observational constraints on EoS parameters of emergent universe

Paul

Thakur²

2017

Astrophys Space Sci

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Abstract. We investigate emergent universe model using recent observational data for the background tests as well as for the growth tests. The background test data comprises of Hubble data, Baryon Acoustic Oscillation (BAO) data, cosmic microwave background (CMB) shift data, Union compilation data. The observational growth data are obtained from Wiggle-Z measurements and rms mass fluctuations data from Lyman-α measurements at different red shifts. The flat emergent universe model obtained by Mukherjee et. al. is permitted with a non-linear equation of state (in short, EoS) (p = Aρ − Bρ 1 2 ), where A and B are constants. The observed cosmological data are used here to estimate the range of allowed values of EoS parameters numerically. The best-fit values of the EoS and growth parameters are determined making use of chi-square minimization technique. The analysis is carried out here considering the Wang-Steinhardt ansatz for growth index (γ) and growth function (f defined as f = Ω γ m (a)). Subsequently, the best-fit values of the EoS parameters are used to study the evolution of the growth function f , growth index γ, state parameter ω with red shift parameter z. The present value of the parameters, namely, f , γ, ω, Ω m are also estimated. The late accelerating phase of the universe in the model is accommodated satisfactorily.

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Non Singular Origin of the Universe and its Connection to the Cosmological Constant Problem (CCP)

Guendelman

2013

Astrophysics and Space Science Proceedings

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We consider a non singular origin for the Universe starting from an Einstein static Universe in the framework of a theory which uses two volume elements √ −gd 4 x and Φd 4 x, where Φ is a metric independent density, also curvature, curvature square terms, first order formalism and for scale invariance a dilaton field φ are considered in the action. In the Einstein frame we also add a cosmological term that parametrizes the zero point fluctuations. The resulting effective potential for the dilaton contains two flat regions, for φ → ∞ relevant for the non singular origin of the Universe and φ → −∞, describing our present Universe. Surprisingly, avoidance of singularities and stability as φ → ∞ imply a positive but small vacuum energy as φ → −∞. Zero vacuum energy density for the present universe is the "threshold" for universe creation.

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Emergent universe with exotic matter

Abstract: A general framework for an emergent universe scenario has been given which makes use of an equation of state. The general features of the model have also been studied and possible primordial composition of the universe have been suggested.

Cited by 187 publications

References 22 publications

Tunneling and the Emergent Universe scheme in a JBD Theory

Tunneling and the Emergent Universe scheme in a JBD Theory

Observational constraints on EoS parameters of emergent universe

Non Singular Origin of the Universe and its Connection to the Cosmological Constant Problem (CCP)

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