Map of the non-thermal velocity dispersion (σ_nth, left panel) and ratio between non-thermal and thermal contribution to the observed velocity dispersion (σ_nth/σ_th, right panel). In the left panel, the contour levels (dotted contours) range from 0.2 to 0.6 km s^-1, in steps of 0.1 km s^-1, while in the right panel they range from 1 to 6, in steps of 1. Crosses and solid contours indicate the millimetre continuum cores and the N₂D⁺ cores, respectively, as in Figs. 3 and 1.