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

TL;DR

This paper explores how Gaussian process reconstructions of Hubble parameter and expansion rate data can help reduce the tension in measurements of the Hubble constant, emphasizing the importance of data quality and future observations.

Contribution

It demonstrates that combining Hubble parameter and expansion rate data with Gaussian processes can improve H0 estimates and potentially alleviate the Hubble tension.

Findings

Simulated data suggest higher H0 values closer to 70 km s$^{-1}$ Mpc$^{-1}$.

Full covariance matrix data lead to higher H0 estimates and uncertainties.

Joint data sets favor higher H0, supporting the potential to resolve the tension.

Abstract

Taking advantage of Gaussian process (GP), we obtain an improved estimate of the Hubble constant, $H_0=70.41\pm1.58$ km s$^{-1}$ Mpc$^{-1}$, using Hubble parameter [$H(z)$] from cosmic chronometers (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 $H_0$. 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 $H_0$ by either using GP reconstruction or fitting them with $E(z)$ data. We find that simulated $H(z)$ data alleviate $H_0$ tension by pushing $H_0$ values higher towards $\sim70$ km s$^{-1}$ Mpc$^{-1}$. We also find that joint $H(z)$ + $E(z)$ data favor higher values of $H_0$, which is also confirmed by constraining $H_0$ in the flat concordance model and 2-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 $H_0$ tension.