Evolution and final fate of massive post-common-envelope binaries

Mergers of neutron stars and black holes are nowadays observed routinely thanks to gravitational-wave astronomy. In the isolated, binary-evolution channel, a common-envelope phase of a red supergiant and a compact object is crucial to sufficiently shrink the orbit and thereby enable a merger via gravitational-wave emission. Here, we use the outcome of three-dimensional hydrodynamic common-envelope simulations of a 9.4 solar mass red supergiant and a 5 solar mass black-hole to explore the further evolution and final fate of the remnant binary. The binary system undergoes another phase of mass transfer during which it is visible as an X-ray binary. We find that the donor star does not explode as an ultra-stripped supernova because of the large remaining envelope mass, but as a Type Ib/c supernova. Supernova kicks are actually required to sufficiently perturb the orbit and thus facilitate a merger within a Hubble time via gravitational-wave emission.