Maps showing H I emission (McClure-Griffiths et al. 2005) (top panel) and ¹²CO emission (Braiding et al. 2018) (bottom panel) in the Westerlund 1 region. Both maps display the emission for an interval in velocity with respect to the local standard of rest of v = [ − 60, −50] km s⁻¹, which approximately corresponds to a distance of 3.9 kpc. The position of Westerlund 1 is marked by the white star symbol and the grey, dashed line shows the Galactic plane. The transparent, white circle marker denotes the centre point with respect to which the radial CR density profiles in Fig. 9a have been computed; the dashed white line displays a circle with radius 1° – up to which the profiles have been computed – around this point. The red lines are contour lines of the flux map shown in Fig. 3a. Regions A, B, and C are the same as in Fig. 3.