PDFs derived from the molecular line maps. The left y-axis gives the normalized probability p(η), the right y-axis the number of pixels per log bin. The upper x-axis is the visual extinction and the lower x-axis the logarithm of the normalized column density. For the CO lines, we fitted a lognormal to the low column-density range, indicated by a green curve. The red line shows the power-law fit to the high column-density end for C¹⁸O, CS, and N₂H⁺. The respective slopes s (and errors) are given in the panels. For the CO lines, the peak and width of the PDF is indicated with A_vpeak and σ.