Marginalised posterior distributions for ṅ₀ using two SMBHB population models. The orange and green open histograms show marginalised posteriors for the agnostic and astrophysically-informed models, respectively. The filled-green histogram shows the prior for the astrophysically-informed model (the prior for the agnostic model is uniform in the range [ − 20, 3]). The vertical dotted lines show the 5th and 95th percentiles of the posteriors.