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

摘要

We searched for the presence of Al-26 in deep-sea sediments as a signature of supernova influx. Our data show an exponential dependence of Al-26 with the sample age that is fully compatible with radioactive decay of terrigenic Al-26. The same set of samples demonstrated a clear supernova Fe-60 signal between 1.7 and 3.2 Myr ago. Combining our Al-26 data with the recently reported Fe-60 data results in a lower limit of 0.18(-0.08)(+0.15) for the local interstellar Fe-60/Al-26 isotope ratio. It compares to most of the ratios deduced from nucleosynthesis models and is within the range of the observed average galactic Fe-60/Al-26 flux ratio of (0.15 +/- 0.05).