Double Neutron-Star Formation from Supernova Natal Kicks

A neutron star emerging from the common-envelope phase may be paired with a helium-star companion. The helium star may eventually undergo a supernova explosion and form a double neutron-star system. Compact-binary population-synthesis codes often treat the transition from the pre-supernova to the post-supernova state as an instantaneous process. We investigate this phase transition with a more sophisticated model that accounts for the finite timescales of the supernova mass loss and natal kick. We compare how treating the finite timescales affects the final orbital characteristics of double neutron star populations with those predicted from the prescriptions often used in binary population-synthesis codes.