Density evolution of the neutrino component at z = 2 (left panels), z = 1 (central panels), and z = 0 (right panels), when M_ν = 0.1 eV (top), M_ν = 0.4 eV (central), and M_ν = 0.8 eV (bottom). All the simulations have a box size of 25 h^-1 Mpc and resolution N_p = 192³/type. Because they are free-streaming, the effect of neutrinos is similar to a Gaussian noise component for very small masses, but as the mass increases, clustering effects are noticeable and are more pronounced for larger neutrino masses and lower redshifts.