The Simplest Parametrization of the Equation of State Parameter in the Scalar Field Universe

Abstract

In this paper, we investigate a scalar field cosmological model of accelerating Universe with the simplest parametrization of the equation of state parameter of the scalar field. We use H(z) data, pantheon compilation of SN Ia data and BAO data to constrain the model parameters using the χ2 minimization technique. We obtain the present values of Hubble constant H0 as 66.2−1.34+1.42, 70.7−0.31+0.32 and 67.74−1.04+1.24 for H(z), H(z) + Pantheon and H(z) + BAO respectively. In addition, we estimate the present age of the Universe in a derived model t0=14.38−0.64+0.63 for joint H(z) and pantheon compilation of SN Ia data which has only 0.88σ tension with its empirical value obtained in Plank collaboration. Moreover, the present values of the deceleration parameter q0 come out to be −0.55−0.038+0.031, −0.61−0.021+0.030 and −0.627−0.025+0.022 by bounding the Universe in the derived model with H(z), H(z) + Pantheon compilation of SN Ia and H(z) + BAO data sets, respectively. We also have performed the state-finder diagnostics to discover the nature of dark energy.