Best-fit MOLPOP-CEP CO model applied to the [C I] and [C II] emission. The different two-component model is given in the x-axis of the plot, the squares show the absolute lowest χ² model from the CO emission (i.e., the black lines in Fig. 8), the triangle shows the contribution from the scaled PDR or XDR model contributing to the high-J transitions, likewise the circle shows the contribution from the PDR log(G₀) = 0.0 component, and the lightly colored circles show models within 1σ of the lowest χ². Note that the error on the magnification factor is not propagated through to the error on the intensity.