Effects of the Metallicity on Li and B Production in Supernova Neutrino Process

TL;DR

This study investigates how stellar metallicity influences the production of lithium-7 and boron-11 in supernova neutrino processes, revealing that metallicity significantly affects yields and the 7Li/11B ratio.

Contribution

It provides a detailed analysis of metallicity effects on Li and B production in supernovae, incorporating updated progenitor models and nuclear reaction networks.

Findings

Yields of 7Li and 11B depend strongly on metallicity.

Higher metallicity leads to fewer neutrons during the $ u$-process.

The 7Li/11B ratio varies with metallicity, being 0.93 at solar metallicity.

Abstract

The neutrino process ($\nu$-process) for the production of 7Li and 11B in core-collapse supernovae (SNe) is extensively investigated. Initial abundances of s-nuclei and other physical conditions are derived from an updated calculation of the SN 1987A progenitor. The nuclear reaction network including neutrino reactions is constructed with the variable order Bader-Deuflhard integration method. We find that yields of 7Li and 11B significantly depend on the stellar metallicity while they are independent of the weak s-process during the stellar evolution. When the metallicity is high, there are more neutron absorbers, i.e., 56Fe, 14N (from initial CNO nuclei), and 54Fe, and the neutron abundance is small during the $\nu$-process. Since 7Be is predominantly destroyed via 7Be(n,p)7Li, a change in the neutron abundance results in different 7Be yields. Then, the calculated yield ratio 7Li/11B=0.93 for the solar metallicity is larger than that for the SN 1987A 7Li/11B=0.80 by 16 % in the inverted mass hierarchy case. We analyze contributions of respective reactions as well as abundance evolution, and clarify the $\nu$-process of 7Li and 11B.