Average infrared luminosity versus proxy (stellar mass as a proxy on the left panel and FUV magnitude on the right). The green squares and blue circles are the average IR luminosities on the stacks at z ∼ 4.5 and z ∼ 5.5, respectively. The black error bars show the population variance (σ_pop), the colored error bars show the photometric noise (σ_phot, see Eq. (1), Sect. 3.1). The open squares are the flux measurements on stacks below mass limit M_lim. The stars are the results on stacks excluding the galaxies with signs of possible contamination by a close companion. The green and blue dashed lines are the best fits of the relation and the thin lines of corresponding color are the MCMC chain realizations of the fit. Top panels: S/N on each stack.