The survival of nuclei in jets associated with core-collapse supernovae
  Heavy nuclei such as nickel-56 are synthesized in a wide range of core-collapse supernovae (CCSN), including energetic supernovae associated with gamma-ray bursts (GRBs). Recent studies suggest that jet-like outflows are a common feature of CCSN. These outflows may entrain synthesized nuclei at launch or during propagation, and provide interesting multi-messenger signals including heavy ultra-high energy cosmic rays. Here, we investigate the destruction processes of nuclei during crossing from the stellar material into the jet material via a cocoon, and during propagation after being successfully loaded into the jet. We find that nuclei can survive for a range of jet parameters because collisional cooling is faster than spallation. While canonical high-luminosity GRB jets may contain nuclei, magnetic dominated models or low-luminosity jets with small bulk Lorentz factors are more favorable for having a more significant heavy nuclei component. 
Shunsaku Horiuchi, Kohta Murase, Kunihito Ioka, Peter Meszaros
astro-ph.HE astro-ph.SR