Left: maser emission distribution per spaxel as observed by dividing integrated intensities of the maser methanol line at 84.5 GHz by the mean intensity value of the surrounding (in terms of E_up/k) methanol lines in LTE at 218.4 and 310.1 GHz (see Sect. 5.2). A 3σ clipping was applied in all the transitions involved to produce the figure. The center and edges of the inner Lindblad resonance from Iodice et al. (2014) are denoted with a black ellipse and dash-dotted gray ellipses, respectively. Regions where we observe methanol maser emission in the J₋₁ → (J − 1)₀ − E line series are labeled in red. Right: same spaxels (with their values as colors) as in the figure to the left, but this time distributed according to their ratios in the SiO/HNCO (y-axis) and CN/C¹⁷O line ratio maps in ALMA band 3. A logarithmic stretch has been applied in both panels for an easy visualization. Colors are in common for both panels. Our threshold of 3.3 above the rotation diagram fit given in Fig. 6 (first panel) corresponds to an intensity ratio of > 0.1244 (see Appendix F).