Study of non-canonical scalar field model using various parametrizations of dark energy equation of state

Abstract

In this present work, we try to build up a cosmological model using a non-canonical scalar field within the framework of a spatially flat FRW space-time. In this context, we have considered four different parametrizations of the equation of state parameter of the non-canonical scalar field. Under this scenario, analytical solutions for various cosmological parameters have been found out. It has been found that the deceleration parameter shows a smooth transition from a positive value to some negative value which indicates that the universe was undergoing an early deceleration followed by late time acceleration which is essential for the structure formation of the universe. With these four parametrizations, the future evolution of the models are also discussed. It has been found that one of the models (Generalized Chaplygin gas model, GCG) mimics the concordance CDM in the near future, whereas two other models (CPL and JBP) diverge due to future singularity. Finally, we have studied these theoretical models with the latest datasets from SN Ia + H (z) + BAO/CMB.

Reconstruction of interaction rate in holographic dark energy model with Hubble horizon as the infrared cut-off

“…It is evident from figure 4 that q(z) shows a smooth transition from a decelerated (q > 0) to an accelerated (q < 0) phase of expansion of the universe at the transition redshift z t = 0.7 +0.02 −0.02 (within 1σ errors) and z t = 0.7 +0.05 −0.05 (within 2σ errors) for the best-fit model. This results are found to be consistent with the results obtained independently by several authors (see [67][68][69] and references there in), which states that the universe at redshift in between z t ∼ 0.5 − 1 underwent a phase transition from decelerating to accelerating expansion. Furthermore, we have also reconstructed the EoS parameter ω DE (z) for the dark energy in figure 5.…”

“…This is essential for the structure formation of the universe. In addition, the best-fit value of the transition redshift (z t = 0.7 +0.05 −0.05 , at 2σ level) obtained in this work is found to be consistent with the results obtained independently by several authors [67][68][69]. Furthermore, it has also been found that for the best-fit model, the evolution of ω DE shows a little phantom nature at the present epoch, which is well consistent with the Planck 2015 data [5].…”

Constraints on reconstructed dark energy model from SN Ia and BAO/CMB observations

“…For the best-fit model, the present value of ω φ (z) comes out to be −0.99 +0.04 −0.03 (with 1σ errors) and −0.99 +0.08 −0.07 (with 2σ errors), which is definitely within the constraint range [60,61]. Moreover, our results are also in good agreement with other previous works [38][39][40][41], where the authors have considered different table 2). The 1σ and 2σ confidence regions have been shown and the central dark line represents the best fit curve.…”

“…In literature, there are many examples where the authors had proposed different redshift parametrizations of ω φ to fit with observational data [34][35][36][37] (for review, see also Refs. [38][39][40][41]). However, it has been found that the parametrization of the energy density ρ φ (z) (which depends on its EoS parameter through an integral) provides tighter constraints than ω φ (z) from the same observational dataset (for details, see Refs.…”

Parametrizations of dark energy models in the background of general non-canonical scalar field in D-dimensional fractal universe

“…For instance, the k-essence is one of the simple form of a non-canonical scalar field model. In the present work, we will consider non-canonical scalar field model with general form of k-essence Lagrangian [58,59,60,61,62,63,64].…”