Hubble parameter measurement constraints on the cosmological deceleration-acceleration transition redshift

TL;DR

This study compiles 28 Hubble parameter measurements across redshifts 0.07 to 2.3 to constrain dark energy models and confirms the universe's current acceleration at over 3-sigma confidence, estimating the transition redshift around 0.74.

Contribution

It provides new constraints on the cosmological deceleration-acceleration transition redshift using an expanded set of H(z) measurements.

Findings

Current acceleration confirmed at >3-sigma confidence.

Transition redshift estimated at z_da = 0.74 ± 0.05.

Results agree with previous BAO-based determinations.

Abstract

We compile a list of 28 independent measurements of the Hubble parameter between redshifts 0.07 < z < 2.3 and use this to place constraints on model parameters of constant and time-evolving dark energy cosmologies. These H(z) measurements by themselves require a currently accelerating cosmological expansion at about, or better than, 3-sigma confidence. The mean and standard deviation of the 6 best-fit model deceleration-acceleration transition redshifts (for the 3 cosmological models and 2 Hubble constant priors we consider) is $z_{\rm da} = 0.74 \pm 0.05$, in good agreement with the recent Busca et al. (2012) determination of $z_{\rm da} = 0.82 \pm 0.08$ based on 11 H(z) measurements between redshifts 0.2 < z < 2.3, almost entirely from BAO-like data.