Model predictions for the underlying (intrinsic) BBH population (grey) and the O3 detected BBH population (orange) for our reference model with α_CE = 1.0 and η_acc = 1. We show the joint distributions of chirp mass M_chirp and effective inspiral spin parameter χ_eff for the combined CE and SMT channels (left), CE formed BBHs (centre) and SMT formed BBHs (right). Lighter colours represent larger contour levels of 68%, 95% and 99%, respectively, constructed with pygtc module (Bocquet & Carter 2016). All histograms are plotted with 30 bins in the same range without any bin smoothing. We overlaid in grey the O1, O2 and O3a LVC GWTC-2 data with their 90% credible intervals. The 9 events of GWTC-2 in tension with our models are indicated in red (see Sect. 3.3), GW190521 is outside the plotted window.