Is there evidence for dark energy evolution?

TL;DR

This paper investigates whether current observational data on the Hubble parameter $H(z)$ supports the evolution of dark energy, finding persistent discrepancies with the standard $\\Lambda$CDM model across a larger dataset.

Contribution

The study extends previous analyses by using 29 $H(z)$ measurements, providing stronger evidence for potential deviations from the $\\Lambda$CDM model and dark energy evolution.

Findings

Discrepancy between observations and $\\Lambda$CDM predictions persists.

The $Omh^2$ diagnostic shows dependence on summary statistics but still indicates tension.

Results support the possibility that dark energy evolves over time.

Abstract

Recently, Sahni, Shafielo o & Starobinsky (2014) combined two independent measurements of $H(z)$ from BAO data with the value of the Hubble constant $H_0 = H(z=0)$, in order to test the cosmological constant hypothesis by means of an improved version of the $Om$ diagnostic. Their result indicated a considerable tension between observations and predictions of the $\Lambda$CDM model. However, such strong conclusion was based only on three measurements of $H(z)$. This motivated us to repeat similar work on a larger sample. By using a comprehensive data set of 29 $H(z)$, we find that discrepancy indeed exists. Even though the value of $\Omega_{m,0} h^2$ inferred from $Omh^2$ diagnostic depends on the way one chooses to make a summary statistics (weighted mean or the median), the persisting discrepancy supports the claims of Sahni, Shafielo o & Starobinsky (2014) that $\Lambda$CDM model may not be the best description of our Universe.