Collapsar Disks and Winds

Winds blown from collapsar accretion disks may produce observable stellar explosions independent of any GRB‐(and afterglow)‐producing jets which may be simultaneously produced. The production of winds is controlled by the accretion disk physics, in particular, the nature of disk cooling via neutrino emission and photo‐disintegration of heavy nuclei. These temperature‐dependent processes depend on the stellar angular momentum via the depth of the gravitational potential at the Kepler radius where the disk forms. Wind‐driven stellar explosions which do not make a GRB (or only a faint one) may occur and constitute a new class of supernova explosion. SN1998bw and 1997ef may be examples. A key feature of collapsar winds is that they are capable of producing the radioactive ⁵⁶Ni necessary to power a supernova light curve. It is possible to make a GRB in a star without significant production of ⁵⁶Ni. Such a star would not make an observable supernova and no such component would be expected in the light curve of the optical afterglow.