Production of 44Ti and Iron-group Nuclei in the Ejecta of 3D Neutrino-driven Supernovae

The radioactive isotopes 44Ti and 56Ni are important products of explosive nucleosynthesis, which play a key role in supernova (SN) diagnostics and have been detected in several nearby young SN remnants. However, most SN models based on nonrotating single stars predict yields of 44Ti that are much lower than the values inferred from observations. We present, for the first time, the nucleosynthesis yields from a self-consistent three-dimensional SN simulation of a ∼19 M⊙ progenitor star that reaches an explosion energy comparable to that of SN 1987A and that covers the evolution of the neutrino-driven explosion until more than 7 s after core bounce. We find a significant enhancement of the Ti/Fe yield compared to recent spherically symmetric (1D) models and demonstrate that the long-time evolution is crucial to understanding the efficient production of 44Ti due to the nonmonotonic temperature and density history of the ejected material. Additionally, we identify characteristic signatures of the nucleosynthesis in proton-rich ejecta, in particular high yields of 45Sc and 64Zn.