2D-histograms of the change in guiding radius ∆R_g between two snapshots separated by ∆t = 0.5 Gyr, with respect to the initial guiding radius R₀. From top to bottom, each row represents stars from Model1, Model2 and Model3. Each column represents a different time in the galaxies’ evolution, increasing from left to right. These times are taken randomly, and the time interval is bigger than that used in section 4. The solid black and pink lines indicate respectively the bar radius and the CR. Strong ridges near these two radii are present in all models. However, the varying amplitude seen in Fig. 2 are not visible here. Model3 shows decreasing ridge amplitude, most likely as a sign of the galaxy getting hotter with time through numerical heating and absence of cold gas accretion (so less sensitive to perturbations).