CO(1−0) emission spectra at different positions in the observed data cube (solid line), the best model cube (black dashed line) and a rejected model cube (grey dashed line). The spatial positions in the galaxy for each spectrum, in arcseconds, are given in the subpanels. The model shows a good agreement with the observations. The positions (–1.2, 5.8) and (–1.2, –5.5) correspond to the “twin peaks” described in Sect. 3.1