Results of tests using abundance profiles from chemical models. The blue curve shows the results of the non-LTE modelling using the abundance profiles of N₂H⁺ and N₂D⁺ predicted from the chemical model presented in Sipilä et al. (2019). The green dashed and red dotted curves instead use a chemical model with a radial dependence of the cosmic-ray ionisation rate, with the high model (H) and with the low model (L) from Padovani et al. (2018), respectively.