Possible indication for non-zero neutrino mass and additional neutrino species from cosmological observations

Understand

The constraints on total neutrino mass and effective number of neutrino species based on CMB anisotropy power spectrum, Hubble constant, baryon acoustic oscillations and galaxy cluster mass function data are presented.

• It is shown that the discrepancies between various cosmological data in Hubble constant and density fluctuation amplitude, measured in standard LCDM cosmological model, can be eliminated if more than standard effective number of neutrino species and non-zero total neutrino mass are considered.
• This extension of LCDM model appears to be \approx 3 \sigma\ significant when all cosmological data are used.
• The model with approximately one additional neutrino type, N_eff \approx 4, and with non-zero total neutrino mass, \approx 0.5 eV, provide the best fit to the data.