Hubble Parameter and Baryon Acoustic Oscillation Measurement Constraints on the Hubble Constant, the Deviation from the Spatially-Flat $\Lambda$cdm Model, The Deceleration-Acceleration Transition Redshift, and Spatial Curvature

TL;DR

This study compiles Hubble parameter data up to redshift 2.36, uses Gaussian Processes to analyze the data, and constrains cosmological parameters like the Hubble constant, transition redshift, and spatial curvature, finding results consistent with a flat universe and lower H0 values.

Contribution

It provides a comprehensive analysis of H(z) data with Gaussian Processes, offering updated constraints on H0, the deceleration-acceleration transition redshift, and spatial curvature.

Findings

H0 estimated at ~67 km/s/Mpc, aligning with lower recent measurements.

Deceleration-acceleration transition occurs at z between 0.33 and 1.0.

Spatial curvature parameter Omega_K0 consistent with zero within large error bars.

Abstract

We compile a complete collection of reliable Hubble parameter $H(z)$ data to redshift $z \leq 2.36$ and use them with the Gaussian Process method to determine continuous $H(z)$ functions for various data subsets. From these continuous $H(z)$'s, summarizing across the data subsets considered, we find $H_0\sim 67 \pm 4\,\rm km/s/Mpc$, more consistent with the recent lower values determined using a variety of techniques. In most data subsets, we see a cosmological deceleration-acceleration transition at 2$\sigma$ significance, with the data subsets transition redshifts varying over $0.33<z_{\rm da}<1.0$ at 1$\sigma$ significance. We find that the flat-$\Lambda$CDM model is consistent with the $H(z)$ data to a $z$ of 1.5 to 2.0, depending on data subset considered, with 2$\sigma$ deviations from flat-$\Lambda$CDM above this redshift range. Using the continuous $H(z)$ with baryon acoustic oscillation distance-redshift observations, we constrain the current spatial curvature density parameter to be $\Omega_{K0}=-0.03\pm0.21$, consistent with a flat universe, but the large error bar does not rule out small values of spatial curvature that are now under debate.