Stellar matter: supernovae as sources of r-process elements ((17) M06)

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The rapid neutron capture process (r-process) is the mechanism by which at least half of the elemental abundances greater than iron are produced in the universe. Its site remains unknown and determining where it occurs is one of the most outstanding questions to be answered in nuclear astrophysics. Present theoretical candidate sites are core collapse supernovae (CCSNe) and binary neutron star mergers. Present state of the art 3D supernova models are too computationally expensive to compute outwards to sufficiently long times, post explosion, to do detailed nucleosynthesis calculations (an issue for which improvement is sought in project M04). As such, the present state of the art models must instead rely on parametric, or spherically symmetric, neutrino wind calculations to estimate the nucleosynthetic output of CCSNe. At present, these models suggest CCSNe are a less favourable site than binary neutron star mergers, but the neutrino microphysics within these models suffer from uncertainties which affect their nucleosynthesis predictions. A finding on Earth of 244Pu coincident in time, at 2 Myr ago, with previously discovered supernova-produced 60Fe would demonstrate that the r-process does occur in CCSNe, answering the outstanding question for the site of the r-process, while simultaneously providing immediate empirical insight to our understanding of the role of neutrinos in r-process nucleosynthesis.