Is it time to go beyond $\Lambda$CDM universe?

TL;DR

This paper revisits constraints on dark energy using recent cosmological data, finding that while some diagnostics suggest deviations from $ ext{Lambda}$CDM, the model remains the best fit overall.

Contribution

It provides updated constraints on dark energy evolution and tests the $ ext{Lambda}$CDM model against recent observational data using the CPL parametrisation.

Findings

$ ext{Lambda}$CDM is inconsistent at 95% confidence level based on dark energy equation of state.

The $Om$ diagnostic still supports $ ext{Lambda}$CDM with a lower $ ext{Omega}_{m0}$ than Planck-2015.

The measured $S$ parameter aligns with KiDS survey results.

Abstract

Concordance $\Lambda$CDM universe is the simplest model that is consistent with a large variety of cosmological observations till date. But few recent observations indicate inconsistencies in $\Lambda$CDM model. In this paper, we consider the combination of recent SnIa+Bao+Cmb+Growth+$H(z)$+$H_{0}$ measurements to revisit the constraints on the dark energy evolution using the widely studied CPL parametrisation for the dark energy equation of state. Although the reconstructed behaviour for the dark energy equation of state confirms the inconsistency of $\Lambda$CDM at $95\%$ confidence level, the reconstructed $Om$ diagnostic which is a {\it null test} for $\Lambda$CDM, still allows the concordance $\Lambda$CDM behaviour with a lower range of $\Omega_{m0}$ than that obtained by Planck-2015. {\it This confirms that $\Lambda$CDM is still the best choice for the dark energy model}. We also measure the parameter $S = \sigma_{8}\sqrt{\Omega_{m0}/0.3} = 0.728 \pm 0.023$ which is consistent with its recent measurement by KiDS survey. The confidence contour in the $\Omega_{m0}-\sigma_{8}$ parameter plane is also fully consistent with KiDS survey measurement.