Evolutionary tracks of SMBH binaries for different values of M _c = 10 ⁷, 10 ⁵  M _☉ and , 10 ⁻², labeled on the panels. Tracks for q = 1 (solid black) and 10 ⁻² (dotted red) are shown and in each panel we consider two starting values of the binary semi-major axis r _b (0). The layout of these plots and meaning of different curves and labels are the same as in Figure  5. In particular, the dashed and dot-dashed curves show the runs of r _infl (Equation (60)) and r _Edd (Equation (72)), respectively, and the black square dots mark the transition to the GW-dominated orbital decay. The open pentagons mark the possible onset of gas overflow; see Section 6.2.7. See the text for a detailed description of the evolution.