Difference between observed CRIR and the model-ℒ to better illustrate the local effects, ∆ log₁₀ ζ = log₁₀ ζ_obs − log₁₀ ζ_model The red and blue colors show the excess and deficiency of CRIR with respect to the expected value following Padovani et al. (2018). The contours correspond to the Herschel-based H₂ column map; the contours are the same as in Fig. 2. The beam size and scale bar are shown in the top-let and bottom-right corners, respectively.