Emission line ratio maps for CO(6−5)/CO(3−2) (top panel), HCO⁺(4−3)/CO(3−2) (middle panel) and HCN(4−3)/HCO⁺(4−3) (bottom panel). For the CO(6−5)/CO(3−2) map, the CO(6−5) data were smoothed to the resolution of the CO(3−2) data, while for the HCN(4−3)/HCO⁺(4−3) map, the HCO⁺(4−3) was truncated to velocities < 15 km s⁻¹ in order to match the velocity coverage of the HCN(4−3) line.