Redshift evolution of the Hubble constant: Constraints and new insights from an interacting dark energy model

TL;DR

This paper proposes an interacting dark energy model that explains the redshift evolution of the Hubble constant, potentially addressing the Hubble tension by fitting diverse cosmological observations.

Contribution

It introduces a new IDE model with a redshift-dependent $H_0$, supported by observational data, and explores its implications for the Hubble tension.

Findings

$H_0$ decreases with redshift according to late-Universe data.

CMB data constrains the interaction parameter to the order of $10^{-5}$.

Dark-sector interactions are suppressed at high redshifts due to baryon--photon coupling.

Abstract

We develop a modified interacting dark energy (IDE) model to study the redshift evolution of the Hubble constant ($H_0$), in light of the Hubble tension. In this framework, the energy exchange between dark energy and dark matter induces a redshift dependence of $H_0$. We evaluate the model against a comprehensive suite of observations, including baryon acoustic oscillations (BAO) from DESI DR2 and SDSS, cosmic chronometers, type Ia supernovae from the Pantheon sample, and Planck CMB distance priors. Analysis of late-Universe data yields $\alpha = 0.0107^{+0.0032}_{-0.011}$, with the best-fit value on the order of $10^{-2}$, revealing a decreasing trend of $H_0$ with redshift. This supports a power-law evolution beyond $\Lambda$CDM. Incorporating CMB data further tightens the constraint to the order of $10^{-5}$, which we attribute to the suppression of dark-sector interactions at high redshifts, a consequence of the strong baryon--photon coupling. These results indicate that the IDE framework provides a theoretically consistent and observationally viable mechanism for describing the redshift evolution of $H_0$, offering a promising avenue toward alleviating the Hubble tension.