Pixel-by-pixel distribution of integrated N₂H⁺ (top panels) and HCN (bottom panels) as a function of ¹²CO emission, similar to Fig. 2 (a) in linear (left panels) and logarithmic (right panels) scaling. Subsets of pixels isolated in Fig. 2 are marked accordingly (pink: subset (c) SW.Arm, yellow: Subset (b) AGN). Power-law fits to the full data (black dashed), the data without the central points (black dotted) and the subsets are added (colors respectively). Fit uncertainties are only shown in log space to ease visibility.