Evolution of the fraction of co-rotational energy as a function of the time since the pericentre passage for low (left) and high (right) κ sub-sample as classified by the 5th and 95th percentiles of the z = 0 κ distribution in Fig. 2. Contours show 75, 50, 25, and 5% of the maximum counts of the 2D distribution. The cyan solid line shows the median value at each time bin. For bins in which less than 50% of the sample entered the median calculation, we instead use a dashed line. The red and blue horizontal dash-dotted lines show the κ threshold values for the low and high κ sub-samples, respectively. The pericentre is marked with a vertical dashed line. In each panel we additionally show the evolution of a galaxy from the corresponding sub-sample using green square markers. The shaded red and blue regions show the allowed κ values corresponding to each sub-sample.