Neutrino masses and cosmic radiation density: Combined analysis

We determine the range of neutrino masses and cosmic radiation content allowed by the most recent CMB and large-scale structure data. In contrast to other recent works, we vary these parameters simultaneously and provide likelihood contours in the two-dimensional parameter space of Neff , the usual effective number of neutrino species measuring the radiation density, and ∑ mν . The allowed range of ∑ mν and Neff has shrunk significantly compared to previous studies. The previous degeneracy between these parameters has disappeared, largely thanks to the baryon acoustic oscillation data. The likelihood contours differ significantly if ∑ mν resides in a single species instead of the standard case of being equally distributed among all flavors. For ∑ mν = 0 we find 2.7 < Neff < 4.6 at 95% CL while ∑ mν < 0.62 eV at 95% CL for the standard radiation content. Neutrino masses and cosmic radiation density: Combined analysis 2