Relative EP heating map for κ = 1. Ratio Γ_EP/Γ_tot as a function of radius R (AU) and height Z/R; colours show the fraction on a logarithmic scale from 10⁻³ to 1. The red contour encloses the zone where EPs are efficiently accelerated (E_max > 10 MeV). The solid black contour marks where EP heating contributes at least to 5% of the total heating (Γ_EP/Γ_tot = 0.05), which is considered to be a significant contribution. The dashed lines delimit the disc surface between column densities of 10¹⁹–10²¹ cm⁻².