Top panels: compact emission traced by the ALMA 12 m + 7 m arrays without TP. Bottom panels: diffuse molecular emission obtained by subtracting the compact emission channel by channel (top panels) from the total molecular emission measured by ALMA 12 m + 7 m + TP (i.e. including short spacings): this is the emission that is filtered out by the interferometer. Left panels: zeroth-order moment maps, measuring the integrated intensity (in K km s⁻¹). Middle panels: first-order moment maps, representing the velocity field (in km s⁻¹). Right panels: second-order moment maps, tracing CO linewidths (σ in km s⁻¹). In all panels, the grey circle in the bottom right represents the FWHM of the synthesised beam (6.3″).