Search for supernova-produced 60Fe in a marine sediment

摘要

An 60Fe peak in a deep-sea FeMn crust has been interpreted as due to thesignature left by the ejecta of a supernova explosion close to the solar system2.8 +/- 0.4 Myr ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. Toconfirm this interpretation with better time resolution and obtain a moredirect flux estimate, we measured 60Fe concentrations along a dated marinesediment. We find no 60Fe peak at the expected level from 1.7 to 3.2 Myr ago.However, applying the same chemistry used for the sediment, we confirm the 60Fesignal in the FeMn crust. The cause of the discrepancy is discussed.