What do parameterized <i>Om</i> ( <i>z</i> ) diagnostics tell us in light of recent observations?

Abstract In this paper, we propose a new parametrization for 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 the ΛCDM model and observations. Our results demonstrate that H 0 plays a very important role in the consistency test of ΛCDM with H ( z ) data. Adopting the Hubble constant priors from Planck 2013 and Riess, one finds considerable tension between the current H ( z ) data and ΛCDM model and confirms the conclusions obtained previously by others. However, with the Hubble constant prior taken from WMAP9, the discrepancy between H ( z ) data and ΛCDM 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 Joint Light-curve Analysis (JLA) SN Ia sample. The best-fit Hubble constant from the combination of H ( z )+JLA ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>H</mml:mi> <mml:mn>0</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>68.81</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.49</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.50</mml:mn> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> km s −1 Mpc −1 ) is very consistent with results derived both by Planck 2013 and WMAP9, but is significantly different from the recent local measurement by Riess.

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