Random Angular Momentum in Convection: Implications for Supergiant Collapse to Form Black Holes

Red supergiants (RSGs) comprise the vast majority of stars that will undergo core collapse. A fraction of these events may not lead to an energetic explosion of the star. Rather, a large fraction of the hydrogen envelope remains bound to the newly-formed black hole (BH). The angular momentum content of the infallling material determines whether accretion power can be liberated into driving an outflow or powering a luminous transient. In this presentation, I will use results from 3D hydrodynamic simulations of idealized models of supergiant convection and collapse to show that the specific angular momentum due to random convective flows implies associated circularization radii that are many hundreds of times the radius of the innermost stable circular orbit of the BH. Our simulations indicate that otherwise failed explosions of non-rotating RSGs may lead to the formation of rotationally-supported flows that are capable of driving outflows to large radii and powering observable transients.