Forward modelling the O3(a+b) GW transient mass distributions with BPASS by varying compact remnant mass and SNe kick prescriptions

We present forward modelling from the BPASS code suite of the population of observed gravitational wave (GW) transients reported by the LIGO/VIRGO consortium (LVC) during their third observing run, O3(a+b). Specifically, we predict the expected chirp mass and mass ratio distributions for GW transients, taking account of detector sensitivity to determine how many events should have been detected by the current detector network in O3(a+b). We investigate how these predictions change by alternating between four different remnant mass estimation schemes and two supernovae (SNe) kick prescriptions. We find that none of the model populations resulting from these variations accurately match the whole O3(a+b) GW transient catalogue. However, agreement from some models to part of the catalogue suggests ways to achieve a more complete fit. These include reducing the number of low-mass black holes (BHs) close to the mass gap, while also increasing the number of higher mass BHs below the pair-instability SN limit. Finally, we find that the interaction between the value of the remnant mass from a stellar model and the choice of SN kick is complex and different kick prescriptions may be required depending on whether a neutron star or BH is formed.