Numerical simulations of the random angular momentum in convection: Implications for supergiant collapse to form black holes

During the core collapse of massive stars that do not undergo a canonical energetic explosion, some hydrogen envelope red supergiant (RSG) progenitor may infall onto newborn black hole (BH). Within Athena++ framework, we perform three-dimensional, hydrodynamical simulations idealized models convection and in order to assess whether convective can give rise rotationally-supported material, even if star has zero angular momentum overall. Our dimensionless, polytropic are applicable optically-thick non-rotating RSGs cover factor 20 stellar radius. At all radii, specific due random flows implies associated circularization radii 10 - 1500 times innermost stable circular orbit BH. collapse, vector is approximately conserved slowly varying on timescale relevant forming disks at small radii. results indicate otherwise failed explosions lead formation capable driving outflows large powering observable transients. When BH able accrete most envelope, final spin parameter $\sim$ 0.5, though non-rotating. For fractional accretion generally lower never exceeds 0.8. We discuss implications our for transients produced by RSG hole.