Deep-Sea and Lunar Radioisotopes from Nearby Astrophysical Explosions

Abstract

Live (not decayed) radioisotopes on the Earth and Moon are messengers from recent nearby astrophysical explosions. Measurements of 60Fe in deep-sea samples, Antarctic snow, and lunar regolith reveal two pulses about 3 Myr and 7 Myr ago. Detection of 244Pu in a deep-sea crust indicates a recent r-process event. We review the ultrasensitive accelerator mass spectrometry techniques that enable these findings. We then explore the implications for astrophysics, including supernova nucleosynthesis, particularly the r-process, as well as supernova dust production and the formation of the Local Bubble that envelops the Solar System. The implications go beyond nuclear physics and astrophysics to include studies of heliophysics, astrobiology, geology, and evolutionary biology.

Could a Kilonova Kill: A Threat Assessment

“…These emissions were seen in many bands from radio to X-ray (Abbott et al 2017b), and the GRB afterglow has been observed for over 4 yr since the merger . 10 It was suggested in Ellis et al (1996) to search for live (not decayed) radioactive isotopes deposited on Earth by nearby SN explosions, and recent geological and lunar data have made it clear that near-Earth explosions are an astrophysical reality (for recent reviews, see Fields & Wallner 2023;Korschinek & Faestermann 2023). Live 60 Fe signals have been measured by many groups in deep-ocean deposits (Knie et al 2004;Fitoussi et al 2008;Ludwig et al 2016;Wallner et al 2016Wallner et al , 2021, Antarctic snow (Koll et al 2019), and in lunar regolith (Fimiani et al 2016).…”

Neutrino-driven Outflows and the Elemental Abundance Patterns of Very Metal-poor Stars

“…Detection of 244 Pu and 60 Fe in deep-sea crust sediments on Earth suggests a core-collapse supernovae contribution for these specific isotopes. However, NSMs can also account for the production of 244 Pu (Wallner et al 2021;Fields & Wallner 2023;Wang et al 2023;Wehmeyer et al 2023).…”