Probability distribution of the velocity dispersion of the diffuse gas. This distribution represents model galaxies with M_⋆ >  10⁷ M_⊙ and at z = 1.1. We compare this distribution with observational measurements from Swinbank et al. (2017, dark blue histrogram) and Pelliccia et al. (2017, light blue histrogram). The solid and dashed vertical lines represent the median and mean value of the distribution of our modelled galaxies, respectively.