Evidence of core collapse in satellites in SIDM (left) as opposed to CDM (right). The figure shows evolutionary tracks of individual satellites on the ﹩{r}_{{\rm{\max }}}﹩–﹩{v}_{{\rm{\max }}}﹩ plane. The color of a dot along the track indicates the cosmic time as shown in the color bar. Satellites were selected to have a resolved ﹩{r}_{{\rm{\max }}}﹩ at all times and to be DM dominated (M_DM > 0 and N_DM > N_⋆).