The phase diagram of the disc for M_• = 10⁵ M_⊙ (top left), 10⁷ M_⊙ (top right) and 10⁹ M_⊙ (bottom) and for different binary semimajor axes, orbital periods and mass ratios. Colours show the relative brightening of the disc outside the secondary relative to the same region of a solitary disc. Three zones can be distinguished as marked: ‘gap’ in which the tidal torque can support a gap against viscosity even in steady state, ‘no gap’ in which the gap overflows in steady state with the tidal torque in the linear regime all the way to the Hill sphere or ‘no gap with torque cutoff’ in which the torques are saturated outside the Hill sphere. We do not show comparable mass ratios (q > 0.1) where the adopted perturbative tidal torque formula and the axisymmetric steady-state approximations are strongly violated.