Common envelope evolution of massive stars

The discovery via gravitational waves of binary black hole systems with total masses greater than 60M_⊙ has raised interesting questions for stellar evolution theory. Among the most promising formation channels for these systems is one involving a common envelope binary containing a low metallicity, core helium burning star with mass ⁓30 - 40M_⊙ and a black hole with mass ⁓30 - 40M_⊙. For this channel to be viable, the common envelope binary must eject more than half the giant star's mass and reduce its orbital separation by as much as a factor of 80. We discuss issues faced in numerically simulating the common envelope evolution of such systems and present a 3D AMR simulation of the dynamical inspiral of a low-metallicity red supergiant with a massive black hole companion.