Figure 6

Contour plot of $Im(\rho )$ in the complex λ plane for the two species example illustrated in Figures 3, 4 and 5 with $v_p\approx 1.54$. (The appropriate choice of $v_p$ is given by (3.24).) Poles and saddle points are indicated by grey and white markers respectively; branch cuts are labelled with thick grey lines. Arrows indicate the direction of increasing $Re(\rho )$.