Arm-interarm gas abundance variations explored with MUSE: the role of spiral structure in the chemical enrichment of galaxies

Abstract

Spiral arms are the most characteristic features of disc galaxies, easily distinguishable due to their association with ongoing star formation. However, the role of spiral structure in the chemical evolution of galaxies is unclear. Here, we explore gas-phase abundance variations between arm and interarm regions for a sample of 45 spiral galaxies using high spatial resolution VLT/MUSE integral field spectroscopy data. We report the presence of more metal-rich H II regions in the spiral arms with respect to the corresponding interarm regions for a large subsample of galaxies (45-65 per cent depending on the adopted calibrator for the abundance derivation). A small percentage of the sample is observed to display the opposite trend, i.e. more metal-poor H II regions in the spiral arms compared to that of the interarms (5-20 per cent depending on the calibrator). We investigate the dependence of the variations with three galaxy properties: the stellar mass, the presence of bars, and the flocculent/grand design appearance of spiral arms. In all cases, we observe that the arm interarm abundance differences are larger (positive) in more massive and grand-design galaxies. This is confirmed by an analogous spaxel-wise analysis, which also shows a noticeable effect of the presence of galactic bars, with barred systems presenting larger (positive) arm-interarm abundance variations than unbarred systems. The comparison of our results with new predictions from theoretical models exploring the nature of the spirals would highly impact on our knowledge on how these structures form and affect their host galaxies.