Collapsar Simulations: From Engine to Relativistic Outflow, and 56Ni Production

摘要

I have developed two-dimensional general relativistic magnetohydrodynamic (GRMHD) code. I have performed numerical simulations of collapsars using these codes and realistic progenitor models. In the GRMHD simulation, it is shown that a jet is launched from the center of the progenitor. We also performed two-dimensional hydrodynamic simulations in the context of collapsar model to investigate the explosive nucleosynthesis happened there. It is found that the amount of ~(56)Ni is very sensitive to the energy deposition rate. This result means that the amount of synthesized ~(56)Ni can be little even if the total explosion energy is as large as 10~(52) erg. Thus, some GRBs can associate with faint supernovae. Thus we consider it is quite natural to detect no underlying supernova in some X-ray afterglows.