Pulsational pair-instability supernovae: gravitational collapse, black hole formation, and beyond

We investigate the final collapse of rotating and non-rotating pulsational pair-instability supernova progenitors with zero-age-main-sequence masses of 60, 80, and 115 M-circle dot and iron cores between 2.37 and 2.72 M-circle dot by 2D hydrodynamics simulations. Using the general relativistic NADA-FLD code with energy-dependent three-flavour neutrino transport by flux-limited diffusion allows us to follow the evolution beyond the moment when the transiently forming neutron star (NS) collapses to a black hole (BH), which happens within 350-580 ms after bounce in all cases. Because of high neutrino luminosities and mean energies, neutrino heating leads to shock revival within less than or similar to 250 ms post bounce in all cases except the rapidly rotating 60 M-circle dot model. In the latter case, centrifugal effects support a 10 per cent higher NS mass but reduce the radiated neutrino luminosities and mean energies by similar to 20 per cent and similar to 10 per cent, respectively, and the neutrino-heating rate by roughly a factor of two compared to the non-rotating counterpart. After BH formation, the neutrino luminosities drop steeply but continue on a 1-2 orders of magnitude lower level for several 100 ms because of aspherical accretion of neutrino and shock-heated matter, before the ultimately spherical collapse of the outer progenitor shells suppresses the neutrino emission to negligible values. In all shock-reviving models BH accretion swallows the entire neutrino-heated matter and the explosion energies decrease from maxima around 1.5 x 10(51) erg to zero within a few seconds latest. Nevertheless, the shock or a sonic pulse moves outward and may trigger mass-loss, which we estimate by long-time simulations with the prometheus code. We also provide gravitational-wave signals.

Automated summary

In this study, the final collapse of rotating and non-rotating pulsational pair-instability supernova progenitors is investigated through 2D hydrodynamics simulations. The results suggest that neutrino heating plays a significant role in shock revival, and after the formation of a black hole, the neutrino luminosities decrease rapidly but continue at a lower level for some time.