Comparison of line luminosities (in solar luminosities) obtained with our six modelling strategies (see summary in Fig. 3), computed for different halo components. Each model is represented by a different colour: SM (grey), MPM+Plummer (purple), MPM+Logotropic (yellow), MPM+Power law (magenta), MPM+2-component Gaussian (orange), and RT (black). Different halo components are indicated using symbols: circle markers for the whole PONOS halo, crosses for the main disc, pentagons for the mergers, and diamonds for the CGM (see Sect. 2.2 or the definition of the components). For the SM, dense gas tracers such as CO are unrealistically low and outside the ranges shown in this plot.