Galactic archaeology with [Mg/Mn] versus [Al/Fe] abundance ratios

Uncertainties and caveats

¹ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via G. B. Tiepolo 11, 34143 Trieste, Italy
² INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
e-mail: arianna.vasini@inaf.it
³ INFN – Sezione di Trieste, via Valerio 2, 34134 Trieste, Italy

Received: 29 July 2023
Accepted: 9 November 2023

Abstract

Context. The diagram depicting the abundance ratios [Mg/Mn] versus [Al/Fe] has gained significant attention in recent literature as a valuable tool for exploring fundamental aspects of the evolution of the Milky Way (MW) and the nearby dwarf galaxies. In particular, this combination of elements is supposed to be highly sensitive to the history of star formation, unveiled by the imprints left on those abundances. Unfortunately, a complete discussion on the uncertainties associated with these nuclei is still missing, making it difficult to know how reliable the associated results are.

Aims. In this work, we aim to analyse, by means of detailed chemical evolution models, the uncertainties related to the nucleosynthesis of Mg, Al, Mn, and Fe to show how different yield prescriptions can substantially affect the trends in the [Mg/Mn] versus [Al/Fe] plane. In fact, if different nucleosynthesis assumptions produce conflicting results, then the [Mg/Mn] versus [Al/Fe] diagram does not represent a strong diagnostic for the star formation history (SFH) of a galaxy.

Methods. We discuss the results on the [Mg/Mn] versus [Al/Fe] diagram, as predicted by several MW and Large Magellanic Cloud (LMC) chemical evolution models adopting different nucleosynthesis prescriptions.

Results. The results show that the literature nucleosynthesis prescriptions require some corrective factors to reproduce the APOGEE DR17 abundances of Mg, Al, and Mn in the MW and that the same factors can also improve the results for the LMC. In particular, we show that by modifying the massive star yields of Mg and Al, the behaviour of the [Mg/Mn] versus [Al/Fe] plot changes substantially.

Conclusions. In conclusion, by changing the chemical yields within their error bars, one obtains trends that differ significantly, making it very difficult to draw any reliable conclusion on the SFH of galaxies. The proposed diagram is therefore very uncertain from a theoretical point of view, and it could represent a good diagnostic for star formation, only if the uncertainties on the nucleosynthesis of the above-mentioned elements (Mg, Mn, Al, and Fe) could be reduced by future stellar calculations.