Early chemical evolution of Zn driven by magnetorotational supernovae and the pathway to the solar Zn composition

TL;DR

This paper investigates the origins of zinc in the galaxy, proposing that early zinc was mainly produced by magnetorotational supernovae, with later contributions from thermonuclear supernovae, explaining the solar zinc composition.

Contribution

It identifies magnetorotational supernovae as the primary early source of zinc and suggests a transition to thermonuclear supernovae for later zinc production, providing new insights into galactic chemical evolution.

Findings

Early zinc production linked to magnetorotational supernovae.

Later zinc contribution from thermonuclear supernovae (SNe Ia).

Solar zinc composition results from combined contributions of both supernova types.

Abstract

The site of Zn production remains an elusive and challenging problem in astrophysics. A large enhancement of the [Zn/Fe] ratios of very metal-poor stars in the Galactic halo suggests the death of short-lived massive stars, i.e., core-collapse supernovae (CCSNe), as one major site for Zn production. Previous studies have claimed that some specific CCSNe can produce Zn in sufficient quantities. However, it remains unclear which models can withstand the critical test of observations. Using a Zn abundance feature similar to that of r-process elements in faint satellite galaxies, we find evidence that Zn production took place through much rarer events than canonical CCSNe. This finding can be unified with the implied decrease in the rate of Zn production with an increasing metallicity for Galactic halo stars, which narrows down the major site of Zn production in the early galaxy to magneto-rotational SNe (MR-SNe). On the other hand, in the later phase of galactic evolution, we predict that the major Zn-production site switched from MR-SNe to thermonuclear SNe (SNe Ia). According to this scenario, an accumulation of the contributions from two types of SNe eventually led to the solar isotope composition of Zn which mainly owes 66,68Zn to MR-SNe and 64Zn to SNe Ia triggered by He-detonation. The requirement of Zn production in SNe Ia sheds a new light on the hot debate on the scenario for SN Ia progenitors, suggesting that a He-detonation model might be one major channel for SNe Ia.