Testing Planck 2020 and DESI data on wCDM Models

Abstract

This work delves into the dynamical dark energy models of the wCDM parameterisation that are defined by their equation of state by comparing different, well-known parameterisation models, in an attempt to lessen the tensions of {H_0} and {\sigma_8} by using the latest observational data. This research also tested the newer Planck likelihood and compared it to the previously released dataset of Planck 2018 and the newer BAO data of DESI. The data that was used were: the Cosmic Microwave Background (CMB) data of Planck 2018 and Planck 2020 data; Cosmic Chronometers (CC), a sample of Supernovae Type Ia; and Baryonic Acoustic Oscillations (BAO). A Bayesian analysis was performed to produce the results needed for the analysis. From the analyses, the best-fit values of the parameters show that almost all models are in favour of a phantom Universe when early-time data was used and favours a quintessence Universe when combinations of early-time and late-time data was considered. This study also showed that the new tested data constrained the models better than the previous ones, while also showing that the observation data supports the {\Lambda}CDM model over the dynamical dark energy models