A time-varying deceleration parameter for unified description of cosmological evolution

Abstract

In this paper, we propose a new time-varying deceleration parameter for the description of a unified cosmological evolution (early inflation, deceleration and present acceleration) using Padé approximation. Within the background of Einstein’s general relativity and for a spatially flat homogeneous and isotropic model, the proposed deceleration parameter leads to a variable equation of state of effective matter that serves all matter within EoS [Formula: see text] (quintessence, relativistic and non-relativistic baryonic matter, stiff matter and cosmological constant), exactly in the same order as it required for various evolutionary phases of the universe. We consider a minimally coupled scalar field with self-interacting potential as the only matter source in the universe. The adopted scheme allows us to determine the potential for the scalar field that drives the cosmological evolution proposed by the deceleration parameter. We perform an explicit numerical computation where analytical solutions are not possible. We examine the validity of the model by depicting the statefinder parameters and comparing them with the recent observational outcomes of cosmography.