The r-process nucleosynthesis in core-collapse supernovae with the magneto-rotational instability

We investigate the r-process nucleosynthesis in the ejecta of core-collapse supernovae driven by rotation and magnetic fields. We adopt an explosion model based on axi-symmetric magneto- hydrodynamical simulation with the effects of magneto-rotational instability, which has been mostly ignored in previous studies. The hydrodynamics simulation also employs a very simplified treatment of neutrino transport on explosion dynamics, which includes the increase of explosion energy due to neutrino heating. We found that very neutron-rich matter in the jet-like explosion, producing heavy r-process nuclei, is ejected along the rotational axis driven by strong magnetic pressure. On the other hand, moderate neutron-rich matter is also ejected in the direction of the equatorial plane due to neutrino-heating associated with the magneto-rotational instability. This ejecta produces lighter and intermediate r-process nuclei rather than heavy isotopes A > 130. We compare these results with observed r-process abundances pattern.