Panel a: exampleof the LOS gas-phase column density profiles obtained at the end of the post-processing described in Sect. 4.1 for models with b = 1 and Ṁ = 10⁻³M_⊙ yr⁻¹ and for an arbitrarily chosen source at a distance of 3.5 kpc. For the U_W items in the legend, U and W are R_c (colours) and n_H(r₀) (styles), respectively. Panel b: radial distribution of the gas-phase column densities extracted at the positions A, B, and C in panel a, i.e. the same times as in Fig. 2.