Transition to a fragmented morphology for a galactic disc perturbed by a massive BH. Left-hand panels: Density map of stars with peaks indicated in red. Right-hand panels: Velocity field. A black dot indicates the BH of 1.25 × 10⁷ M_⊙ (or, ≃1% the mass of the stars), with its velocity vector also in black. The configurations are displayed at three different times: 144 (top), 308 (middle), and 452 Myr (bottom row) of evolution. Contour levels in yellow (left-hand panel) and grey (right-hand panel) identify the member stars of the clump formed at t = 452 Myr. The BH sits at ≃52pc of the coordinates centre. The relative velocity between the clump’s centre of mass motion and the BH is indicated with an arrow on both panels, pointing in a north, north-west direction (west is to the left).