Impact of New Gamow-Teller Strengths on Explosive Type Ia Supernova Nucleosynthesis

TL;DR

This paper investigates how recent experimental reductions in Gamow-Teller strengths affect nucleosynthesis predictions in Type Ia supernovae, leading to more accurate electron-capture rates and improved modeling of explosive burning phases.

Contribution

It introduces a shell model parametrization that aligns more closely with experimental GT strengths and assesses its impact on supernova nucleosynthesis simulations.

Findings

Reduced GT$_+$ strengths slightly increase electron fractions.

New rates lead to different nucleosynthesis outcomes compared to older models.

Improved modeling of explosive burning phases in Type Ia supernovae.

Abstract

Recent experimental results have confirmed a possible reduction in the GT$_+$ strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of Type Ia supernovae. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT$_+$ strength can result in an slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed which more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of Type Ia supernovae, and the final mass fractions are compared to those obtained using more commonly-used rates.