Cosmological bound on neutrino masses in the light of $H_0$ tension

TL;DR

This paper examines how resolving the H0 tension with modified recombination models weakens the cosmological bounds on neutrino masses derived from CMB data.

Contribution

It demonstrates that addressing the H0 tension through modified recombination models significantly relaxes the cosmological constraints on neutrino masses.

Findings

Constraints on neutrino masses are weaker in models resolving the H0 tension.

Modified recombination models can reconcile CMB data with local H0 measurements.

Neutrino mass bounds depend strongly on the assumed cosmological model.

Abstract

Although cosmic microwave background (CMB) is the most powerful cosmological probe of neutrino masses, it is in trouble with local direct measurements of $H_0$, which is called the $H_0$ tension. Since neutrino masses are correlated with $H_0$ in CMB, one can expect the cosmological bound on neutrino masses would be much affected by the $H_0$ tension. We investigate what impact this tension brings to cosmological bound on neutrino masses by assuming a model with modified recombination which has been shown to resolve the tension. We argue that constraints on neutrino masses become significantly weaker in models where the $H_0$ tension can be resolved.