Galaxies with extended mid-IR emission. Left panels: in color are the ALMA MSR 870 μm continuum images (with both the unresolved and the extended emission) from GB21. The blue contours are the mid-IR PSF-subtracted images with the same levels as in Fig. 2. The FoV is 2″ × 2″. We also plot with the dashed lines the approximate PA of the ionization cones, NLR and/or outflows (see Sect. 3.4). Right panels: RGB images constructed with the ALMA CO(3−2) image (red), ALMA 870 μm continuum (green), and extended mid-IR emission (blue). The FoV is approximately the same as in the left panels.