Neutrino Mass Bounds in the Era of Tension Cosmology

The measurements of cosmic microwave background (CMB) anisotropies made by the Planck satellite provide extremely tight upper bounds on the total neutrino mass scale (Sigma m(nu) < 0.26 eV at 95% C.L.). However, as recently discussed in the literature, the Planck data show anomalies that could affect this result. Here we provide new constraints on neutrino masses using the recent and complementary CMB measurements from the Atacama Cosmology Telescope DR4 and the South Pole Telescope SPT-3G experiments. We found that both the ACT-DR4 and SPT-3G data, when combined with WMAP, mildly suggest a neutrino mass with Sigma m(nu) = 0.68 +/- 0.31 and 0.46(-0.36)(+0.14) eV at 68% C.L., respectively. Moreover, when CMB lensing from the Planck experiment is included, the ACT-DR4 data now indicate a neutrino mass above the two standard deviations, with Sigma m(nu) = 0.60(-0.50)(+0.44) eV at 95% C.L., while WMAP+SPT-3G provides a weak upper limit of Sigma m(nu) < 0.37 eV at 68% C.L. Interestingly, these results are consistent with the Planck CMB+lensing constraint of Sigma m(nu) = 0.41(-0.25)(+0.17) eV at 68% C.L. when variations in the A(lens) parameter are considered. We also show that these indications are still present after the inclusion of BAO or Type Ia supernova data in extended cosmologies that are usually considered to solve the so-called Hubble tension. In this respect, we note that in these models, CMB+BAO constraints prefer a higher neutrino mass for higher values of the Hubble constant. A combination of ACT-DR4, WMAP, BAO, and constraints on the Hubble constant from the SHOES collaboration gives Sigma m(nu) = 0.39(+0.25)(+0.13) eV at 68% C.L. in extended cosmologies.

Automated summary

New constraints on neutrino masses are provided using recent and complementary CMB measurements from the Atacama Cosmology Telescope DR4 and the South Pole Telescope SPT-3G experiments. The results indicate a neutrino mass of 0.68 +/- 0.31 eV and 0.46 (-0.36)(+0.14) eV when combined with WMAP, for ACT-DR4 and SPT-3G data respectively.