Radial distribution of the azimuthally averaged H₂ column density as traced by ¹²CO and ¹³CO. We include the radial distribution of N(H₂) from gas associated with spaxels where both ¹²CO and ¹³CO are detected (mask CO2) and where ¹²CO is detected but ¹³CO is not (mask CO1). The total distribution (mask CO1+ mask CO2) has been increased by 20% to account for ¹²CO emission that is not detected in individual spaxels but was detected after averaging them in azimuth (see Sect. 5.2.2).