Comparison of the terms contributing to the overall stack luminosity for a single simulation realisation using the three different CO prescriptions. The top panel shows histograms of the L_CO of each DM halo included in the galaxy catalogue and thus directly selected to be included in the stack. The bottom panel shows the summed L_CO of all the halos neighbouring a given selected halo – these halos also fall into the stack aperture and thus contribute to the stack as well. In both panels, the (linear) averages are shown as vertical lines.