Precision Constraints on New Dark Energy Parametrization from DESI BAO DR2

TL;DR

This paper introduces a new dark energy parametrization deviating from $\\Lambda$CDM, constrained by recent observational data, indicating a non-zero deviation and a dynamic cosmic acceleration history.

Contribution

The study proposes a novel single-parameter dark energy model and provides observational constraints showing deviations from the standard cosmological model.

Findings

Best-fit parameter $\\alpha = 0.239 \\pm 0.07$ at 68\\\% CL.

Hubble constant $H_0 = 68.40 \\pm 0.23$ km/s/Mpc from joint analysis.

Deceleration parameter indicates a transition from deceleration to acceleration and a future return to deceleration.

Abstract

In this article, we investigate a new parametrization of the dark energy equation of state (EoS) with a single parameter for a barotropic fluid that deviates from the standard $\Lambda$CDM cosmology. We derive observational constraints on the model parameters using recent datasets including Observational Hubble Data (OHD), Pantheon+SH0ES (PPS), and Dark Energy Spectroscopic Instrument Baryon Acoustic Oscillations Data Release 2 (DESI BAO DR2). We constrain the best fit value of the parameter as, $\alpha =0.239 \pm 0.07$ at 68\% CL from joint analysis, which is non-null and suggests deviations from the cosmological constant. The model accommodates varying values of Hubble constant from different datasets and joint analysis yields $H_0 = 68.40 \pm 0.23$ $\mathrm{Km\,s^ {-1} Mpc^{-1}}$ at 68\% CL. We examine the physical behavior of the model by analyzing the deceleration parameter, the age of the universe, and the Om(z) diagnose. The deceleration parameter confirms a smooth transition from the past deceleration phase to the present cosmic acceleration as well as and also a second future transition back to deceleration, when PPS data is employed.