Time evolution of the velocity, position and angular momentum of the BH as function of time. The BH initially sits at rest at the system’s barycentre. a) The solid black curve graphs the angular momentum, which shows an irregular pattern of small amplitude; the scale’s upper bound of ≃0.5 is the value expected for a radial orbit with r = 0.125kpc at velocity v_ϕ = 6.6km s¹ ; the right-hand axis in red is the scale for individual velocity components ; b) The radius (in black, left-hand axis) and velocity |v_•| (in turquoise, right-hand axis) as function of time. The arrows indicate the spatial resolution =0.125kpc of the calculation, in black; and the expected velocity for a BH orbiting in the frozen background potential inside its influence radius, here ≃0.180kpc, in turquoise. The black dotted line is the z coordinate. Significant yet resolved motion develops only after a runtime ∼1.5 Gyr.