Cosmological model-independent test of Λ CDM with two-point diagnostic by the observational Hubble parameter data

Abstract

Aiming at exploring the nature of dark energy (DE), we use forty-three observational Hubble parameter data (OHD) in the redshift range 0 < z⩽ 2.36 to make a cosmological model-independent test of the ΛCDM model with two-point Omh2(z2; z1) diagnostic. In ΛCDM model, with equation of state (EoS) w= - 1 , two-point diagnostic relation Omh2≡ Ωmh2 is tenable, where Ωm is the present matter density parameter, and h is the Hubble parameter divided by 100 kms-1Mpc-1. We utilize two methods: the weighted mean and median statistics to bin the OHD to increase the signal-to-noise ratio of the measurements. The binning methods turn out to be promising and considered to be robust. By applying the two-point diagnostic to the binned data, we find that although the best-fit values of Omh2 fluctuate as the continuous redshift intervals change, on average, they are continuous with being constant within 1 σ confidence interval. Therefore, we conclude that the ΛCDM model cannot be ruled out.