SFR–total halo mass relation (median lines through density plots) at z = 3.8. We evaluate the effects of galactic winds (top left panel), AGN feedback (top right panel), metal cooling (bottom left panel) and choice of IMF (bottom right panel). The blue dot–dashed horizontal lines represent the observational limits in the range of SFR of Smit et al. (2012). The orange dot–dashed vertical line is our mass confidence limit (see Section 3.1).