What is the optimum stellar rotation rate for a collapsar?

摘要

We consider low angular momentum, neutrino cooled accretion flows onto newborn black holes in the context of the collapsar model for long gamma-ray bursts, and find a considerable energy release for rotation rates lower than those usually considered. The efficiency for the transformation of gravitational binding energy into radiation is maximized when the equatorial angular momentum l0 ~ 2rgc.