Limits on Supernova-Associated 60Fe/26Al Nucleosynthesis Ratios from Accelerator Mass Spectrometry Measurements of Deep-Sea Sediments


Using accelerator mass spectometry to measure the 26AI content of deep-sea sediments, a limit is established on 60Fe/26 AI nucleosynthesis ratios from recent and local supernova events.

We searched for the presence of 26Al in deep-sea sediments as a signature of supernova influx. Our data show an exponential dependence of 26Al with the sample age that is fully compatible with radioactive decay of terrigenic 26Al. The same set of samples demonstrated a clear supernova 60Fe signal between 1.7 and 3.2 Myr ago. Combining our 26Al data with the recently reported 60Fe data results in a lower limit of 0.18+0.150.08 for the local interstellar 60Fe/26Al isotope ratio. It compares to most of the ratios deduced from nucleosynthesis models and is within the range of the observed average galactic 60Fe/26Al flux ratio of (0.15±0.05).

Supernova © Jenny Feige