Placement of galaxies on the V_rot − V_h diagram. Main figure: the blue line is the average V_rot − V_h relation in a ΛCDM universe, inferred from abundance matching (same as in Fig. 4). The colored points represent a sample of 194 galaxies with interferometric HI observations, drawn from the literature. Their V_rot and V_h values are computed as described in Fig. 5. All points are drawn as upper limits, because we make the conservative assumption that the contribution of baryons to the galactic RC is negligible for all galaxies. Refer to Sects. 3.3 and 4 for the scientific interpretation of this figure. Inset panel: a zoom-in on the low-velocity region of the diagram (linear axes).