Possibility of Secondary i- and s-processes Following r-process in the Collapsar Jet

Abstract The slow and intermediate neutron-capture processes, s - and i -processes, are believed to occur in asymptotic giant branch stars to provide half of the heavy atomic nuclei with A ≥ 90. We suggest a possibility that certain types of outflows found in the collapsar, which is a supernova generated by a rapidly rotating massive star undergoing core collapse, leaving behind a black hole and emitting relativistic jets, can provide conditions that are viable for s - and i -processes as secondary processes following the rapid neutron-capture process, r -process. We propose that the pronounced odd–even effect in the mass abundance pattern near rare earth elements in metal-deficient halo stars could be an observational hint for the s - and i -processes in the collapsar.