A viable dynamic dark energy model with parametrized equation of state

Abstract

A novel and analytically simplifiable parametrization for the equation of state (EoS) of the dark energy, which elegantly captures the universe’s transition from a decelerated matter-dominated era (\(\omega \approx 0\) at high redshift) to the current phase of accelerated expansion (\(\omega \rightarrow -1\) as \(z\rightarrow 0\)) is introduced. The primary focus lies in a comprehensive theoretical formulation of this model within the standard Friedmann framework, deriving key cosmological parameters and exploring the model’s behaviour across cosmic history. This parametrization provides a smooth and physically consistent evolution of the EoS, naturally reproducing the observed transition from deceleration to acceleration around \(z\approx 0.5\), without invoking exotic fields or higher-order corrections. In contrast to conventional parametrized dark energy models such as Chevallier-Polarski-Linder (CPL), Jassal-Bagla-Padmanabhan (JBP), and Barboza-Alcaniz (BA) expansions, the present model stands out for its simplicity, stability, and freedom from divergences across the full redshift range. Using observed Hubble data, best fit values of model parameters are obtained and are consistent with current cosmological parameter values. The state-finder diagnostics and a phase space analysis well support the dynamic dark energy parametrization.