Constraints on dark energy from the Ly{\alpha} forest baryon acoustic oscillations measurement of the redshift 2.3 Hubble parameter

TL;DR

This study combines H(z) measurements from Lyα forest BAO and other sources to constrain dark energy models, finding evidence for acceleration and favoring a cosmological constant but allowing for slow evolution.

Contribution

It introduces new H(z) constraints from Lyα forest BAO measurements, improving limits on dark energy parameters compared to previous studies.

Findings

H(z) constraints are more restrictive than supernova data.

Evidence for accelerating expansion at about 2-sigma confidence.

Data favor a flat universe with a cosmological constant, but allow slow dark energy evolution.

Abstract

We use the Busca et al. (2012) measurement of the Hubble parameter at redshift z = 2.3 in conjunction with 21 lower z measurements, from Simon et al. (2005), Gaztanaga et al. (2009), Stern et al. (2010), and Moresco et al. (2012), to place constraints on model parameters of constant and time-evolving dark energy cosmological models. The inclusion of the new Busca et al. (2012) measurement results in H(z) constraints significantly more restrictive than those derived by Farooq et al. (2012). These H(z) constraints are now more restrictive than those that follow from current Type Ia supernova (SNIa) apparent magnitude measurements (Suzuki et al. 2012). The H(z) constraints by themselves require an accelerating cosmological expansion at about 2-sigma confidence level, depending on cosmological model and Hubble constant prior used in the analysis. A joint analysis of H(z), baryon acoustic oscillation peak length scale, and SNIa data favors a spatially-flat cosmological model currently dominated by a time-independent cosmological constant but does not exclude slowly-evolving dark energy density.