The effect of environment-sensitive, correlated initial conditions on compact object merger population synthesis

The intricacies of star formation have often been underexplored in population synthesis, in contrast to the ample exploration of different evolutionary models. For compact object mergers in particular, which are expected to probe very early star formation, any systematic variations of star formation with cosmic time, such as in the stellar IMF, could leave a measurable imprint on the redshift-evolution of those populations. In this talk, I will describe the effort made with the BOSSA code to consistently implement an environment-sensitive IMF and correlated ZAMS orbital parameters in binary population synthesis, including considerations about multiplicity statistics and the IMF of binary components. I will also report the results of using BOSSA and COMPAS to generate synthetic merger populations under invariant and varying initial condition models, and show that initial conditions can have a significant impact on the redshift-dependent shape of the merger mass distribution.