Radial profiles of some COMs as a function of radial distance moving westwards (left panel) and southwards (right panel) from the SgrB2(N1) hot core with G₀ = 10³. The symbols represent observational data. The prominent solid lines illustrate the best models (the lighter lines denote models corresponding to the ages within ±1σ around the age determined by the best χ²). Our model can nicely reproduce the radial profiles of CH₃OH, CH₃OCH₃, NH₂CHO and CH₃CHO but fails to explain the C₂H₅OH profile. To better match observations for all COMs, the cosmic ray ionisation rate is required to be higher than the typical value of the ISM. For the westwards, ζ_scale = 30 corresponds to ζ(0.2 pc) ≃ 60 × ζ_ISRF, and ζ_scale = 20 corresponds to ζ(0.2 pc) ≃ 50 × ζ_ISRF for the southwards. The best-fit period correspond to (3–7) × 10⁴ yr.