Discovery Prospects for a Supernova Signature of Biogenic Origin

TL;DR

This study suggests that a supernova event 2.8 million years ago left a detectable biogenic signature in Earth's fossil record, specifically in magnetite microfossils produced by bacteria at that time.

Contribution

It proposes a novel method to detect supernova signatures through biogenic magnetite microfossils, linking astrophysical events with Earth's biological record.

Findings

Supernova 60Fe flux estimate matches detection sensitivity.

Biogenic magnetite microfossils contain measurable 60Fe signatures.

Earth's fossil record can reveal ancient cosmic events.

Abstract

Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of 60Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite Fe3O4 microfossils produced by magnetotactic bacteria extant at the time of the Earth-supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using estimates for the terrestrial supernova 60Fe flux, combined with our empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the ^{60}{Fe} fraction as 60Fe/Fe ~ 3.6 x 10^{-15}. This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry capabilities. The implication is that a biogenic signature of this cosmic event is detectable in the Earth's fossil record.