Velocity anisotropy and deviation from sphericity. Left panel: Velocity anisotropy parameter as a function of time for the VlaSolve (solid lines) and Gadget-2 simulations we performed (dashed curves). Right panel: Evolution of the departure from spherical symmetry for the two kind of initial conditions experiencing radial orbit instability in Gadget-2, namely (η, n) = (0.1, −1.0) (blue curves) and (η, n) = (0.1, −1.5) (red curves, solid and dashed for the 10 and 100 million particles simulations, respectively). The quantity indicates the deviation from unity of r_axis (in log scale and with a negative sign for r_axis >  1), where r_axis = b/c (upper curves) or b/a (lower curves), and a ≤ b ≤ c are the principal axis lengths of the Gadget-2 particle distribution derived from the inertia tensor.