Joint distribution of the chirp mass, M_chirp, and the effective inspiral spin parameter, χ_eff, for the combined CE, SMT, and CHE channels. For both sub-figures, the model predictions for the underlying (intrinsic) BBH population are shown in gray, where lighter shades represent larger contour levels of 90% and 99.9%, respectively. Left: detected BBH population with O3 sensitivity, shown in orange. Overlaid in black are the O1, O2, and O3a of the LIGO Scientific and Virgo Collaboration (LVC) GWTC-2 (Abbott et al. 2021a) data with their 90% CIs; GW190521 is outside the plotted window. Right: BBH subpopulation that emitted LGRBs at BBH formation, shown in blue. The ten events in GWTC-2 with chances > 10% of having emitted a luminous LGRB at BBH formation are indicated in black. The two events with > 50% probabilities, GW190517 and GW190719, are indicated with star markers. No bin smoothing was applied when constructing the contour levels.