Probing the dynamics of Gaussian dark energy equation of state using DESI BAO

ABSTRACT We present an updated reconstruction of the dark energy (DE) equation of state (EoS), $w(a)$, employing the newly released Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) baryon acoustic oscillation (BAO) data. This analysis constrains the cosmological scenarios influenced by different models 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 (CPL, PADE, GEDE, GDE, and BellDE) and their interrelations. A Bayesian inference procedure is adopted to estimate the models parameters that yield the best fit to the data. The EoS remains within the phantom regime at higher redshifts, while favouring the quintessence regime in the current epoch. In this context, we propose a new Gaussian-like form of EoS, termed BellDE, which avoids phantom behaviour ($w \ge -1$) at higher redshifts while remaining precisely calibrated at lower redshifts. Interestingly, BellDE exhibits a transient phantom nature ($w < -1$) around the transition redshift $z \sim 0.5$, subsequently evolving into a quintessential regime ($w > -1$). In particular, the BellDE model provides competitive statistical preference while offering greater flexibility in the redshift regime $z \sim 0.5-1$, where DE is observationally significant.