Effects of massive neutrinos on the large-scale structure of the Universe

Cosmological neutrinos strongly affect the evolution of the largest structures in the Universe, i.e. galaxies and galaxy clusters. We use large box-size full hydrodynamic simulations to investigate the non-linear effects that massive neutrinos have on the spatial properties of cold dark matter (CDM) haloes. We quantify the difference with respect to the concordance ΛCDM model of the halo mass function and of the halo two-point correlation function. We model the redshift-space distortions and compute the errors on the linear distortion parameter β introduced if cosmological neutrinos are assumed to be massless. We find that, if not taken correctly into account and depending on the total neutrino mass Mν, these effects could lead to a potentially fake signature of modified gravity. Future nearly all-sky spectroscopic galaxy surveys will be able to constrain the neutrino mass if Mν≳ 0.6eV, using β measurements alone and independently of the value of the matter power spectrum normalization σ8. In combination with other cosmological probes, this will strengthen neutrino mass constraints and help breaking parameter degeneracies.