Perturbed gas surface densities (Σ∕Σ₀) at t = 12 500 orbits of the inner planet, in the Spread (first row) and Compact (second row) configurations. The disks have a small aspect ratio and low viscosity (α = 10⁻⁴). The masses of the planets are reduced by a factor of two-thirds (left panels) and one-half (middle panels). They can be compared to the total mass configuration in the right panels. As in Fig. A.1, the positions of the planets are marked by dots in each panel and the disks can be considered axisymmetric.