Cosmic-ray density profiles above 4 TeV for different velocity intervals. The profiles in the upper plot have been computed with respect to the centre point shown by the circle marker in Fig. 8 (the same as for the excess profiles displayed in Fig. 4), whereas the profiles in the lower plot have been computed with respect to the position of Westerlund 1. The error bars denote the (statistical) uncertainty of the measured γ-ray flux only, and in particular do not reflect systematic uncertainties related to the gas distribution. The CR density at Earth, indicated for comparison, was computed from the all-particle CR spectrum as modelled in Breuhaus et al. (2022) (model ‘A’). The data points taken from Aharonian et al. (2019), shown in the lower plot, have been derived using a velocity interval of v = [ − 60, −50] km s⁻¹, and should thus be compared to the blue curve with circle markers. The red, solid line, from the same paper, shows a profile corresponding to a 1/r-distribution of the CRs, where r is the distance to the cluster. Both show the density above a slightly higher threshold energy of 10 TeV.