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 Ne., the usual effective number of neutrino species measuring the radiation density, and Sigma m(nu). The allowed range of Sigma m(nu) and N-eff 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 Sigma m(nu) resides in a single species instead of the standard case of being equally distributed among all flavours. For Sigma m(v) = 0 we find 2.7 < N-eff < 4.6 at 95% CL while Sigma m(nu) < 0.62 eV at 95% CL for the standard radiation content.