Explosive nucleosynthesis with fast neutrino-flavor conversion in core-collapse supernovae

TL;DR

This study investigates how fast neutrino-flavor conversion (FFC) influences explosive nucleosynthesis in core-collapse supernovae, revealing that FFC affects heavier elements and can alter ejecta composition depending on neutrino emission asymmetry.

Contribution

The paper introduces a parametric analysis of FFC effects on nucleosynthesis considering asymmetric neutrino emission, highlighting its variable impact on ejecta composition.

Findings

FFC influences heavier element synthesis in supernova ejecta.

The impact of FFC varies non-monotonically with neutrino emission asymmetry.

FFC generally promotes neutron-rich ejecta but can produce proton-rich ejecta under certain conditions.

Abstract

Fast neutrino-flavor conversion (FFC) is a possible game-changing ingredient in core-collapse supernova (CCSN) theory. In this paper, we examine the impact of FFC on explosive nucleosynthesis by including the effects of FFC in conjunction with asymmetric neutrino emission into nucleosynthetic computations in a parametric way. We find that the ejecta compositions are not appreciably affected by FFC for elements lighter than Co, while the compositions are influenced by FFC for the heavier elements. We also find that the role of FFC varies depending on the asymmetric degree of neutrino emission ($m_{\rm asy}$) and the degree of neutrino-flavor mixing. The impact of FFC is not monotonic to $m_{\rm asy}$; The change in the ejecta composition increases for higher $m_{\rm asy}$ up to $\sim 10\%$ compared with that without FFC, whereas FFC has little effect on the nucleosynthesis in very large asymmetric neutrino emission ($\gtrsim 30 \%$). Our results suggest that FFC facilitates the production of neutron-rich ejecta in most cases, although it makes the ejecta more proton-rich if anti-neutrino conversion is more vigorous than that of neutrino. The key ingredient accounting for this trend is neutrino absorption, whose effects on nucleosynthesis can be quantified by simple diagnostics.