Study of the cosmological tensions and DESI-DR2 in the framework of the Little Rip model

Abstract

We present an analysis that investigates the $H_0$ and $S_8$ tensions by considering a dark energy model. The latter is a late-time model characterized by a future abrupt event known as the Little Rip (LR) model and characterised by one extra parameter, $\beta$, compared to the standard model, $\Lambda$CDM. To test this approach, we perform a statistical analysis by the MCMC method using the most recent observational data. We obtain a positive correlation in ($H_0$, $\beta$) plane. We also note that the Hubble tension is less than $3\sigma$ when using early measurements, i.e., Cosmic Microwave Background (CMB) data, and when combining it with Baryon Acoustic Oscillation (BAO) data, but it is no longer so when we combine early and late measurements (i.e. PantheonPlus (PP)). In addition, we test the model with DESI-DR2 combined with CMB and recent SNIa measurements. We notice that our model shifts toward the quintessence field. For a complete statistical analysis, we use the Akaike Information Criteria and Bayesian analysis of the evidence. According to Bayes factors, we find that the LR model provides an improved fit only to CMB data.