Distribution of the properties of the population of BNS at their formation (i.e. right after the secondary SN) and at three metallicities: Z = 9.5 × 10⁻⁵ (left), Z = 9.5 × 10⁻⁴ (centre), and Z = 1.4 × 10⁻² (right). From top to bottom, the three rows show the distributions of (1) stellar evolution times, (2) merger times, and (3) delay times. As in Fig. 5, the standard evolutionary track is shown in blue, the equal-mass track in green, and the AIC track in orange. In black, we show the total population. The count sum of the three evolutionary tracks accounts for ∼95% of systems (see Sect. 2.3).