Critical line of stability for various configurations. The vertical axis is the BH mass M_• plotted against azimuthal velocity v_ϕ. At fixed M_•, the minimum azimuthal velocity v_ϕ to reach such that the dynamical traction sets in is found by crossing one of the black curves, from left, to right. Four curves are plotted, each corresponding to a different value of the stellar velocity dispersion σ_⋆ as indicated in the legend. The blue dot marks the estimated coordinates of the Milky Way’s BH. The red curve highlights an asymptotic trend of slop ≃ − 2 found in the limit of low v_ϕ.