Addressing $H_0$ tension by means of VCDM

TL;DR

This paper proposes a minimally modified gravity theory called VCDM to address the H0 tension, allowing for a low-redshift transition in the universe's expansion history, which improves data fit and reduces the H0 discrepancy.

Contribution

The paper introduces VCDM, a new gravity model, demonstrating its ability to fit cosmological data better and alleviate the H0 tension.

Findings

VCDM allows a low-redshift transition at z≈0.3 or 1.8.

Total chi-squared improves by about 12 with VCDM.

Local H0 is estimated as 73.6±1.4 km/s/Mpc, reducing tension.

Abstract

In this letter we propose a reduction of the $H_0$ tension puzzle by means of a theory of minimally modified gravity which is dubbed VCDM. After confronting the theory with the experiments, we find that the data allow for a low-redshift transition in the expansion history of the universe at either $z\simeq 0.3 $ or $z \simeq 1.8\,$, corresponding to one of the two local minima of the total $\chi^2$. From the bestfit values the total fitness parameter is improved by $\Delta \chi^2 \simeq 12$, for the data set considered. We then infer the local Hubble expansion rate today within this theory by means of low redshift Pantheon data. The resulting local Hubble expansion rate today is $H^{\rm{loc}}_0=73.6\pm1.4$. We find the tension is reduced within the VCDM theory.