Electron-capture supernovae as sources of 60Fe

TL;DR

This study models electron-capture supernovae to understand their role in producing the radioactive isotope 60Fe, revealing they contribute significantly to its galactic abundance and co-produce other neutron-rich isotopes.

Contribution

It provides the first detailed two-dimensional simulation of 60Fe nucleosynthesis in ECSNe, highlighting their contribution to galactic 60Fe and associated isotopes.

Findings

ECSNe produce significant amounts of 60Fe, especially in low-entropy conditions.

ECSNe account for 4-30% of live 60Fe in the Milky Way.

ECSNe co-produce neutron-rich isotopes like 48Ca, 50Ti, and 54Cr.

Abstract

We investigate the nucleosynthesis of the radionuclide 60Fe in electron-capture supernovae (ECSNe). The nucleosynthetic results are based on a self-consistent, two-dimensional simulation of an ECSN as well as models in which the densities are systematically increased by some factors (low-entropy models). 60Fe is found to be appreciably made in neutron-rich ejecta during the nuclear quasi-equilibrium phase with greater amounts being produced in the lower-entropy models. Our results, combining them with the yields of core-collapse supernovae (CCSNe) in the literature, suggest that ECSNe account for at least 4-30% of live 60Fe in the Milky Way. ECSNe co-produce neutron-rich isotopes, 48Ca, 50Ti, 54Cr, some light trans-iron elements, and possibly weak r-process elements including some radionuclides such as 93Zr, 99Tc, and 107Pd, whose association with 60Fe might have been imprinted in primitive meteorites or in the deep ocean crust on the Earth.