Potentialities of Hubble parameter and expansion rate function data to alleviate Hubble tension

Abstract

ABSTRACT Taking advantage of Gaussian process (GP), we obtain an improved estimate of the Hubble constant, H0 = 70.41 ± 1.58 km s−1 Mpc−1, using Hubble parameter [H(z)] from cosmic chronometer (CCH) and expansion rate function [E(z)], extracted from Type Ia supernovae, data. We also use CCH data, including the ones with full covariance matrix, and E(z) data to obtain a determination of $H_0=72.34_{-1.92}^{+1.90}$ km s−1 Mpc−1, which implies that the involvement of full covariance matrix results in higher values and uncertainties of H0. These results are higher than those obtained by directly reconstructing CCH data with GP. In order to estimate the potential of future CCH data, we simulate two sets of H(z) data and use them to constrain H0 by either using GP reconstruction or fitting them with E(z) data. We find that the simulated H(z) data alleviate H0 tension by pushing H0 values higher towards ∼70 km s−1 Mpc−1. We also find that joint H(z) + E(z) data favour higher values of H0, which is also confirmed by constraining H0 in the flat concordance model and second-order Taylor expansion of H(z). In summary, we conclude that more and better-quality CCH data as well as E(z) data can provide a new and useful perspective on resolving H0 tension.