SPL fit (green region) of the IllustrisTNG haloes (black dots), to the scaling relation of the mass fraction of baryons f_bar and halo mass M measured by the FoF algorithm, for all redshifts. Each panel is labelled with the corresponding simulation tag and the value of the α_SPL slope in the upper-left corner. The baryon fraction includes all gas and stellar mass within each halo. The yellow region represents the baryon fraction from Planck Collaboration XIII (2016). All regions are in 3σ.