Amplitude of the 2D Fourier transform A(m, p) of the logarithmic surface density (see Equation (10)) in the region 2–4 kpc, integrated over p. Different panels are for runs with ⟨Q⟩ = 1 and varying ℳ_c, evaluated at the same times as in Figure 6. The grey curves are simulation data and the orange ones are the empirical fits to the data (see text for details). We can see how the power shifts toward higher values of m with increasing ℳ_c.