Unveiling ν secrets with cosmological data: Neutrino masses and mass hierarchy

Using some of the latest cosmological data sets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, M_, within the assumption of a background flat cosmology. In the most conservative scheme, combining Planck cosmic microwave background temperature anisotropies and baryon acoustic oscillations (BAO) data, as well as the up-to-date constraint on the optical depth to reionization (), the tightest 95% confidence level upper bound we find is M_0. 06 eV from oscillations data would raise the quoted upper bounds by O (0. 1) and would not affect our conclusions.