QED V: Variations in metal loading of galactic winds with element nucleosynthetic origin

TL;DR

This paper investigates how the metal loading of galactic winds varies with the nucleosynthetic origin of elements, revealing significant differences that impact galaxy formation diagnostics.

Contribution

It demonstrates that metal loading in galactic winds varies substantially between elements from different stellar sources, influenced by galactic environment, challenging previous assumptions.

Findings

Metal loadings differ by about 0.3 dex between elements from different sources.

Differential metal loading varies with galactic environment and is unpredictable a priori.

Implications for interpreting galaxy formation diagnostics based on abundance ratios.

Abstract

Type Ia supernovae, type II supernovae, and asymptotic giant branch (AGB) stars are important sites of stellar nucleosynthesis, but they differ greatly in their rates, their location within a galaxy, and the mean thermal energy and abundance distribution of their ejecta. In earlier papers in this series we have shown that a significant fraction of metals newly synthesized by type II supernovae are promptly lost to galactic winds -- i.e., galactic winds are metal loaded. Here we investigate whether the elements returned by type Ia supernovae and AGB stars are similarly metal loaded, or whether metal loading varies significantly with nucleosynthetic site. We use a series of high-resolution ``tall box'' simulations of the interstellar medium with the \quokka~GPU-accelerated code, within which we systematically vary the galaxy gas surface density, metallicity, and the scale heights and relative rates of the different nucleosynthetic sources. We show that the metal loadings of galactic winds differ substantially between metals produced by different sources, with typical variations at the level of $\approx 0.3$ dex, a phenomenon we term differential metal loading. Which set of metals suffers preferential loss from this phenomenon varies depending on the galactic environment, and is not easily predictable \textit{a priori}. Our findings call into question the the interpretation of diagnostics of galaxy formation, for example star formation timescales and initial mass functions, based on abundance diagnostics, since the abundance variations upon which these techniques rely are often at levels comparable to those we show can be induced by differential metal loading.