Probing the Dynamics of Gaussian Dark Energy Equation of State Using DESI BAO

Abstract: We present an updated reconstruction of the various dark energy equation of state (EoS), $w(a)$, employing the newly released DESI DR2 Baryon Acoustic Oscillation data. This analysis constrains the cosmological scenarios influenced by these equations through the joint examination of a range of recently available cosmological probes, specifically the Pantheon+ sample and the DESY5 sample of Type Ia Supernovae, baryon acoustic oscillations, Hubble parameter measurements derived from cosmic chronometers, and cosmic microwave background distance priors based on the Planck 2018 data. Furthermore, we provide a concise perspective on the dynamical evolution of all models and the interrelations among them. A Bayesian inference procedure is adopted to estimate the model parameters that yield the best fit to the data. The EoS remains within the phantom regime at higher redshifts, while favoring the quintessence regime in the current epoch. In this context, we propose a new Gaussian form EoS, termed BellDE, which avoids phantom behavior ((w \geq -1)) at higher redshifts while remaining precisely calibrated at lower redshifts. Interestingly, BellDE exhibits a transient phantom nature ((w < -1)) only around the transition redshift (z \sim 0.5), subsequently evolving into a quintessential regime ((w > -1)), as indicated by comparisons with the Chevallier-Polarski-Linder (CPL) and other parameterized EoS forms.