Example of frequency analysis of the V_R wave for the Model 1hf at time t = 2 Gyr. Top: blue line is the average V_R as a function of L_Z, while the orange line is in the scale of , shown in the top horizontal axis. Bottom: fourier amplitude as a function of frequency in L_Z (blue and bottom axis) and in (orange, top axis). The frequencies are in units of (km s⁻¹ kpc⁻¹)⁻¹ (blue) and km s⁻¹ kpc⁻¹ (orange).