Orateur
Description
We use the Cosmic Chronometers H(z) data, also the observational H(z) data (OHD), to investigate the universe's evolution, focusing on its applications in constraining cosmological parameters, probing dark energy, and refining methods for determining the Hubble constant (H0). (1) To improve cosmological model selection, we combine H(z) with fσ8(z), comparing the traditional chi-square approach with Linder’s joint H(z)-fσ8 diagram. Our results show that the joint method is more significant than the traditional combined method in constraining the density parameter (ΩM) based on Akaike and Bayesian Information Criteria (see for more details: Niu, J., & Zhang, T.-J. 2023, Physics of the Dark Universe, 39, 101147, doi:10.1016/j.dark.2022.101147, ). (2) In exploring dark energy, we reconstruct the scalar field potential V(φ) using Gaussian process analysis of H(z) data under various priors. We find that the reconstructed V(φ) is highly sensitive to the choice of prior and dataset. Simulations reveal that doubling the H(z) data points improves reconstruction accuracy by 5%–30%, underscoring the importance of data availability (see for more details: Niu, J., et al. 2024, ApJ, 972, 14 doi:10.3847/1538-4357/ad5fef, ). (3) For H0 determination, we evaluate three methods—EMCEE, Gaussian Process (GP), and Masked Autoregressive Flow (MAF). Sensitivity analysis identifies GP as the most influenced by individual data points, while simulations rank EMCEE as the most accurate, followed by MAF and GP.
