The chemical DNA of the Magellanic Clouds

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Abstract
Context . In the context of galactic archaeology, the study of the Small Magellanic Cloud (SMC) is of crucial importance, as it represents a unique opportunity to study a nearby massive dwarf system. However, theoretical studies of the chemical evolution of this galaxy are significantly lacking. Aims . In this study, we investigate the chemical enrichment of the SMC galaxy. In addition to the α and Fe-peak elements, we devote particular attention to the evolution of neutron-capture elements with a different origin; namely, r-process (Eu), weak s-process (Zr) and main s-process (Ba, La). Methods . We developed chemical evolution models that use as their input the star formation histories obtained from colour-magnitude diagram fitting. We closely followed the chemical feedback provided by a large variety of nucleosynthetic sources. Our model predictions were compared with recent abundance measurements for the SMC. Results . The developed framework aptly reproduces all the observables for elements up to the Fe-peak. The abundance patterns of n-capture elements are simultaneously reproduced only by assuming an enhanced contribution from the delayed r-process at low metallicity and a top-lighter IMF relative to the reference IMF by Kroupa 2001 (MNRAS, 322, 231). In this way, both the observed very high plateau in [Eu/Fe] and the rising trends in [s-process/Fe] ratios can be reproduced by the models. Conclusions . This study provides, for the first time, information on the evolution of several n-capture elements in a massive dwarf irregular galaxy, also providing insight on several ingredients driving galactic evolution. Moreover, this work provides a test-bed for further modelling of the SMC in the context of the numerous surveys that will target the Magellanic Clouds in the next years.

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