Updating neutrino mass constraints with Background measurements

Understand

Low-redshift probes, such as Baryon Acoustic Oscillations (BAO) and Supernovae Ia luminosity distances, have been shown to be crucial for improving the bounds on the total neutrino mass from cosmological observations, due to their ability to break degeneracies among the different parameters.

• Here, we expand background observations to include $H(z)$ measurements from cosmic chronometers, distance moduli from Gamma Ray Bursts (GRBs), and angular diameter distances from galaxy clusters.
• For the very first time, we find neutrino mass limits below the minimal expectations from neutrino oscillation probes, suggesting non-standard neutrino and/or cosmological scenarios.
• The tightening of the neutrino mass bound is due to the slightly higher value of the Hubble constant $H_0$ preferred by the former three background probes, and also due to the improved errors on $H_0$ and the matter mass-energy density $\Omega_{\rm m}$.