Azimuthally-averaged radial surface density profiles at different times for nominal disc mass (M) simulations with a Jupiter-mass planet at 5.2 au. Left panel: same as the left panel of Fig. 3 for simulation M_2D, except that the scale on the y-axis is logarithmic, to appreciate the gap’s depth and its evolution with time. Right panel: same for the M_3D simulation. The gaps in 2D and 3D inviscid discs (with adiabatic EoS and a cooling timescale equal to one planet’s orbital period) appear very different; see text for discussion.