Monte Carlo population synthesis on massive star binaries: Astrophysical implications for gravitational wave sources

Understand

There are important but unresolved processes in the standard formation scenarios of double compact star binaries (DCBs; BH-BH, BH-NS, NS-NS systems), such as mass transfer and the common envelope (CE) phase.

• We analyze the effects of different assumptions on key physical processes and binary initial conditions on massive star binary evolution with binary population synthesis (BPS), including a survey of proposed prescriptions for the mass transfer ($\rm q_{\rm cr}$) and the binding energy parameter ($\lambda$) in the CE phase.
• We find that $\rm q_{\rm cr}$ clearly affects the properties of NS-NS systems while $\lambda$ has influence on the mass distributions of BH-BH systems.
• The merger rates of DCBs are increased by efficient CE ejection, which in our prescription is related to the binding energy parameter including all the possible budgets to the energy content.