Ultra-delayed Neutrino-driven Explosion of Rotating Massive-star Collapse

Long-term neutrino-radiation hydrodynamics simulations in full general relativity are performed for the collapse of rotating massive stars that are evolved from He-stars with initial masses of 20 and 32 M_⊙. It is shown that if the collapsing stellar core has sufficient angular momentum, the rotationally supported proto-neutron star (PNS) survives for seconds accompanying the formation of a massive torus of mass larger than 1 M_⊙. Subsequent mass accretion onto the central region produces a massive and compact central object, and eventually enhances the neutrino luminosity beyond 10⁵³ erg s^-1, resulting in a very delayed neutrino-driven explosion, in particular toward the polar direction. The kinetic energy of the explosion can be appreciably higher than 10⁵² erg for a massive progenitor star and compatible with that of energetic supernovae like broad-line type-Ic supernovae. By the subsequent accretion, the massive PNS collapses eventually into a rapidly spinning black hole, which could be a central engine for gamma-ray bursts if a massive torus surrounds it.