What is parameterized $Om(z)$ diagnostics telling us in light of recent observations?

TL;DR

This study introduces a new parametrization of the $Om(z)$ diagnostic to test the $ ext{Lambda}$CDM model against recent $H(z)$ and SNe Ia data, revealing the crucial influence of $H_0$ priors on model consistency.

Contribution

It proposes a novel $Om(z)$ parametrization and analyzes how different $H_0$ priors affect the consistency between observations and $ ext{Lambda}$CDM.

Findings

High $H_0$ priors from Planck and Riess show tension with $ ext{Lambda}$CDM.

Using WMAP9 $H_0$ prior, data supports the cosmological constant scenario.

Combined $H(z)$ and SNe Ia data yield a $H_0$ consistent with Planck and WMAP9.

Abstract

In this paper, we propose a new parametrization of $Om(z)$ diagnostics and show how the most recent and significantly improved observations concerning the $H(z)$ and SN Ia measurements can be used to probe the consistency or tension between $\Lambda$CDM model and observations. Our results demonstrates that $H_0$ plays a very important role in the consistency test of $\Lambda$CDM with the $H(z)$ data. Adopting the Hubble constant priors from \textit{Planck} 2013 and Riess (2016), one finds a considerable tension between the current $H(z)$ data and $\Lambda$CDM model and confirms the conclusions obtained previously by the others. However, with the Hubble constant prior taken from WMAP9, the discrepancy between $H(z)$ data and $\Lambda$CDM disappears, i.e., the current $H(z)$ observations still support the cosmological constant scenario. This conclusion is also supported by the results derived from the JLA SNe Ia sample. The best-fit Hubble constant from the combination of $H(z)$+JLA ($H_0=68.81^{+1.50}_{-1.49}$ km/s/Mpc) is well consistent with the results derived both by Planck 2013 and WMAP9, which is significantly different from the recent local measurement by Riess (2016).