Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis


Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis

Wallner, A.; Faestermann, T.; Feige, J.; Feldstein, C.; Knie, K.; Korschinek, G.; Kutschera, W.; Ofan, A.; Paul, M.; Quinto, F.; Rugel, G.; Steier, P.

Half of the heavy elements including all actinides are produced in r-process nucleosynthesis, whose sites and history remain a mystery. If continuously produced, the Interstellar Medium is expected to build up a quasi-steady state of abundances of short-lived nuclides (with half-lives ≤100My), including actinides produced in r-process nucleosynthesis. Their existence in today’s Interstellar Medium would serve as a radioactive clock and would establish that their production was recent. In particular 244Pu, a radioactive actinide nuclide (81My half-life), can place strong constraints on recent r-process frequency and production yield. Here we report the detection of live interstellar 244Pu, archived in Earth’s deep-sea floor during the last 25My, at abundances lower than expected from continuous production in the Galaxy by about two orders of magnitude. This large discrepancy may signal a rarity of actinide r-process nucleosynthesis sites, compatible with neutron-star mergers or with a small subset of actinide-producing supernovae.

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Publ.-Id: 21064