Evolution of radial Lovelace parameter (see Eq. (8)) and Σ profiles during vortex formation over the first 200 orbits of the sample case from Sect. 3. The vertical lines indicate the center of the plateau in (estimated by eye) to guide the eye to the corresponding location of the Σ profile. is calculated as the azimuthal average at each radius. The dotted horizontal line in the bottom panel marks 10% of Σ₀, which we define as the location of the gap edge.