Observational constraints on EoS parameters of emergent universe

Abstract

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.

Emergent universe in $$D \ge 4$$ dimensions with dynamical wormholes

“…3, the interesting aspect of A is that it takes the role of the EoS parameter ω, the change in the behaviour of NEC near t = 0 indicates a transition from normal matter to exotic matter phase. The late accelerating phase of the universe in the EU model can be described satisfactorily [77][78][79][80][81][82][83]. The nEoS is equivalent to a composition of three different types of fluids namely, dark energy (DE), dark matter (DM) and normal matter, which later transform from one sector to the other due to interaction that sets in among them accommodating observed universe which is discussed in Sect.…”

“…EU model also accommodates the observed universe fairly well [69]. In the literature [70][71][72][73][74][75][76][77][78][79][80][81][82][83], EU model is implemented in a number of gravitational theories and found to work satisfactorily. We demonstrate here the emergent universe [69] model in the usual 4 and in higher dimensions making use of the nEoS with γ = 1 2 which is given by…”

“…Subsequently, a flat EU model was obtained with nEoS in GR [69]. Flat EU model is also implemented in different theories of gravity [70][71][72][73][74][75][76] with the observed features [77][78][79][80][81][82][83]. The nEoS [69] p = Aρ − B √ ρ o ρ that admits an EU model, permits three different barotropic fluids determined by A and B.…”

On cosmology of interacting varying polytropic dark fluids

“…In the last 3 equations σ µ is the uncertainty in the distance modulus [43]. We will follow to the receipt of Ref.…”

Primordial Power Spectra from an Emergent Universe: Basic Results and Clarifications

“…As examples, one can think to (some versions of) nonlinear sigma models [20], Horava-Lifshitz gravity [21,22], Einstein-Gauss-Bonnet theory [23], exotic matter [24], branes [25], Kaluza-Klein cosmology [26], particle creation mechanism [27], microscopic effects [28], quantum reduced loop gravity [29], and quintom matter (see [30] for the background dynamics and [31] for the associated perturbations). This leads to interesting consequences reviewed for example in [32][33][34][35][36].…”