Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53Mn, 60Fe, 182Hf, and 244Pu into Deep-sea Archives. Surfing the Wave?

While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a three-dimensional GCE model, we investigated the evolution of four SLRs: Mn-53, Fe-60, Hf-182, and Pu-244 with the aim of explaining detections of recent (within the last approximate to 1-20 Myr) deposition of live Mn-53, Fe-60, and Pu-244 of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneous arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar Mn-53, Fe-60, and Pu-244 are found within the same, or similar, layers of deep-sea sediments. We predict that Hf-182 should also be found in such sediments at similar depths.

Automated summary

Modeling the evolution of short-lived radioisotopes provides supplementary timing information on recent nucleosynthesis. Using a three-dimensional galactic chemical evolution model, we investigated the evolution of four short-lived radioisotopes and found that core-collapse supernovae are the dominant propagation mechanism. This explains why live extrasolar Mn-53, Fe-60, and Pu-244 are found within the same or similar layers of deep-sea sediments and predicts that Hf-182 should also be found at similar depths.