Predicted space velocities and rotational velocities of OB stars with bound and unbound NS and BH companions with observations of the transverse velocities of isolated SMC OBe stars (blue line and small dots), BeXBs (large blue dots), and SMC X-1 (grey). The median error of the transverse velocities is 23 km/s. Centre: space velocity–rotational velocity plane. Top: space velocities coloured by SN type. The part of the histogram within the grey line indicates the unbound systems. Right: rotational velocities coloured by SN type.