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

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