(a) Boundary between inward and outward migration according to Equation (6) for an adiabatic disk with power-law indices α for surface density and β for temperature. (b) Boundary between faster forced migration of inner planet and faster forced migration of outer planet according to Equations (7) and (8) for m ₁ = m ₂. (c) Combined plot, with the convergent outward and inward migration regions corresponding to the regions bounded by the red and blue lines in Figure 3.