Distribution for the FWHM derived across all the cuts in each fiber radial profile. (Left panel) Histogram of the fiber FWHM divided per region. (Right panel) Cumulative distribution of the same FWHM per fiber cut. The dashed black line in the left panel corresponds to the characteristic FWHM measured in parsec-scale filaments in the Solar neighbourhood (e.g. Arzoumanian et al. 2011) while a dotted grey line indicates the minimum size (3 × θ_beam) for our fibers to be considered as resolved by our observations.