Ratio of the moment of inertia matrix principal axes b/a and c/a for the second generation of stars ɡ2. The vertical line at −5.1Gyr shows the two-body relaxation time (900 Myr). A rapid change is visible much earlier on: a few times the 100 Myr VRR timescale (Eq. (4)). The solid lines represent TNG, the dashed lines are the FIX potentials, and the dot-dashed lines are the isolated cases.