2015MNRAS.454..637G

We study the accretion along streams from the cosmic web into high-redshift massive galaxies using three sets of AMR hydrocosmological simulations. We find that the streams keep a roughly constant accretion rate as they penetrate into the halo centre. The mean accretion rate follows the mass and redshift dependence predicted for haloes by the EPS approximation, {dot}M ∝M_vir^1.25 (1 + z)^2.5. The distribution of the accretion rates can well be described by a sum of two Gaussians, the primary corresponding to `smooth inflow' and the secondary to `mergers'. The same functional form was already found for the distributions of specific star formation rates in observations. The mass fraction in the smooth component is 60-90 percent, insensitive to redshift or halo mass. The simulations with strong feedback show clear signs of reaccretion due to recycling of galactic winds. The mean accretion rate for the mergers is a factor 2-3 larger than that of the smooth component. The standard deviation of the merger accretion rate is 0.2-0.3 dex, showing no trend with mass or redshift. For the smooth component it is 0.12-0.24 dex.