Explosive Nucleosynthesis from Gamma‐Ray Burst and Hypernova Progenitors: Direct Collapse versus Fallback

The collapsar engine behind long-duration gamma-ray bursts extracts theenergy released from the rapid accretion of a collapsing star onto astellar-massed black hole. In a collapsing star, this black hole can form intwo ways: the direct collapse of the stellar core into a black hole and thedelayed collapse of a black hole caused by fallback in a weak supernovaexplosion. In the case of a delayed-collapse black hole, the strongcollapsar-driven explosion overtakes the weak supernova explosion before shockbreakout, and it is very difficult to distinguish this black hole formationscenario from the direct collapse scenario. However, the delayed-collapsemechanism, with its double explosion, produces explosive nucleosynthetic yieldsthat are very different from the direct collapse scenario. We present1-dimensional studies of the nucleosynthetic yields from both black holeformation scenarios, deriving differences and trends in their nucleosyntheticyields.Comment: 47 pages, submitted to Ap