Gas column and number density in the vicinity of Cyg OB2. Top panel: total target column density considering the ISM in the neutral and molecular phases. The column density of HI has been evaluated using the 21 cm line observation from the CGPS, while for the molecular gas, we used a combination of ¹²CO observations from the Nobeyama radio telescope and the data from the ¹²CO galactic plane survey by Dame et al. (2001). All the observations are kinematically cut selecting only the gas between −20 and 20 km s⁻¹. White rings represent the regions used by Aharonian et al. (2019) and Abeysekara et al. (2021) to probe the γ-ray radial profile. The radii of the different circles correspond to angular sizes of 0.61°, 1.19°, 1.8° and 2.21°. Bottom panel: average gas density profile in the Cygnus region for each annulus.