THE<i>r</i>-PROCESS NUCLEOSYNTHESIS IN THE VARIOUS JET-LIKE EXPLOSIONS OF MAGNETOROTATIONAL CORE-COLLAPSE SUPERNOVAE

Abstract

The r-process nucleosynthesis in core-collapse supernovae (CC-SNe) is\nstudied, with a focus on the explosion scenario induced by rotation and strong\nmagnetic fields. Nucleosynthesis calculations are conducted based on\nmagneto-hydrodynamical explosion models with a wide range of parameters for\ninitial rotation and magnetic fields. The explosion models are classified in\ntwo different types: i.e., prompt-magnetic-jet and delayed-magnetic-jet, for\nwhich the magnetic fields of proto-neutron stars (PNSs) during collapse and the\ncore-bounce are strong and comparatively moderate, respectively. Following the\nhydrodynamical trajectories of each explosion model, we confirmed that\nr-processes successfully occur in the prompt-magnetic-jets, which produce heavy\nnuclei including actinides. On the other hand, the r-process in the\ndelayed-magnetic-jet is suppressed, which synthesizes only nuclei up to the\nsecond peak ($A \\sim 130$). Thus, the r-process in the delayed-magnetic-jets\ncould explain only "weak r-process" patterns observed in metal-poor stars\nrather than the "main r-process", represented by the solar abundances. Our\nresults imply that core-collapse supernovae are possible astronomical sources\nof heavy r-process elements if their magnetic fields are strong enough, while\nweaker magnetic explosions may produce "weak r-process" patterns ($A \\lesssim\n130$). We show the potential importance and necessity of magneto-rotational\nsupernovae for explaining the galactic chemical evolution, as well as\nabundances of r-process enhanced metal-poor stars. We also examine the effects\nof the remaining uncertainties in the nature of PNSs due to weak interactions\nthat determine the final neutron-richness of ejecta. Additionally, we briefly\ndiscuss radioactive isotope yields in primary jets (e.g., $^{56}$Ni), with\nrelation to several optical observation of SNe and relevant high-energy\nastronomical phenomena.\n