Super and massive AGB stars - IV. Final fates - Initial to final mass relation

TL;DR

This study models the evolution and final fates of super-AGB and massive AGB stars across various metallicities, providing new insights into their mass thresholds, supernova types, and initial-final mass relations.

Contribution

It offers a detailed theoretical initial to final mass relation and constrains the mass limits for different stellar end states, including white dwarfs and supernovae, across a range of metallicities.

Findings

Electron-capture supernova rates are lower at low metallicities.

The EC-SN channel is very narrow in initial mass (~0.2 Msun).

CO cores cannot grow enough to cause Type 1.5 supernovae.

Abstract

We explore the final fates of massive intermediate-mass stars by computing detailed stellar models from the zero age main sequence until near the end of the thermally pulsing phase. These super-AGB and massive AGB star models are in the mass range between 5.0 and 10.0 Msun for metallicities spanning the range Z=0.02-0.0001. We probe the mass limits M_up, M_n and M_mass, the minimum masses for the onset of carbon burning, the formation of a neutron star, and the iron core-collapse supernovae respectively, to constrain the white dwarf/electron-capture supernova boundary. We provide a theoretical initial to final mass relation for the massive and ultra-massive white dwarfs and specify the mass range for the occurrence of hybrid CO(Ne) white dwarfs. We predict electron-capture supernova (EC-SN) rates for lower metallicities which are significantly lower than existing values from parametric studies in the literature. We conclude the EC-SN channel (for single stars and with the critical assumption being the choice of mass-loss rate) is very narrow in initial mass, at most approximately 0.2 Msun. This implies that between ~ 2-5 per cent of all gravitational collapse supernova are EC-SNe in the metallicity range Z=0.02 to 0.0001. With our choice for mass-loss prescription and computed core growth rates we find, within our metallicity range, that CO cores cannot grow sufficiently massive to undergo a Type 1.5 SN explosion.