Model Selection Using Cosmic Chronometers with Gaussian Processes

TL;DR

This paper employs Gaussian Processes with cosmic chronometers to reconstruct the Hubble constant in a cosmology-independent way, favoring the R_h=ct universe over other models based on observational data.

Contribution

It introduces a cosmology-independent method using Gaussian Processes to reconstruct H(z) from cosmic chronometers, providing a new way to test cosmological models.

Findings

Reconstructed H(z) has less than 9% dispersion over 0<z<2.

The R_h=ct universe is favored over Planck LCDM based on the reconstructed H(z).

Standard model parameters can be re-optimized but yield lower p-values.

Abstract

The use of Gaussian Processes with a measurement of the cosmic expansion rate based solely on the observation of cosmic chronometers provides a completely cosmology-independent reconstruction of the Hubble constant H(z) suitable for testing different models. The corresponding dispersion sigma_H is smaller than ~9% over the entire redshift range (0 < z < 2) of the observations, rivaling many kinds of cosmological measurements available today. We use the reconstructed H(z) function to test six different cosmologies, and show that it favours the R_h=ct universe, which has only one free parameter (i.e., H_0) over other models, including Planck LCDM. The parameters of the standard model may be re-optimized to improve the fits to the reconstructed H(z) function, but the results have smaller p-values than one finds with R_h=ct.