Priors for the initial positions in our simulation, shown by seeding 10³ points and displaying their density in normalised 2D histograms with bins of 0.5 kpc. The left panel shows the exponential disc prior from Disberg et al. (2024), and the right panel shows the Gaussian annulus prior as defined in Eq. (5). The black stars show the positions of the Galactic BNSs, determined as the mean of the Monte Carlo distributions described in Sect. 2.2 (cf. Gaspari et al. 2024). The dotted lines show R = R⊙ ± 2 kpc, which traces the edges of the solar neighbourhood (as defined by Disberg et al. 2024).