Surface brightness profile of the dust distribution of the galaxy J081740, the other galaxies are shown in Fig. B.1. Left panel: surface brightness map of the dust continuum. The emission is shown as contours in orange for the data and in violet for the best-fit model. The contour levels follow levels of emission of 4σ, 8σ and 16σ, where σ is the RMS noise in the total map. We show the beam of the observations in the bottom left. Middle panel: residual map normalised by the RMS noise according to the colourbar shown. We show the centre of the best-fit model of the galaxy with a small cross. Right panel: 1D profile of the average gas emission in concentric ellipses (orange) and the best-fit Sérsic model (violet), the black dotted line shows the 4σ level above the noise.