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Observational analysis revealed no significant difference in star formation efficiency between spiral arms and interarm regions, suggesting a gathering role of spiral arms.
The role of spiral arms in galaxies -- whether they enhance star formation efficiency or primarily act as material gatherers -- remains an open question. Observational studies have yielded ambiguous results, in part due to the choice of star formation rate (SFR) tracers and their inherent limitations. These limitations are addressed here by applying multi-wavelength spectral energy distribution (SED) fitting to individual arm and interarm regions. We expand on our previous study of two galaxies to include six diverse galaxies, spanning over an order of magnitude in total stellar mass and factors of several in total SFR, for which spiral arms have been mapped. We find that the specific star formation rate (sSFR = SFR/Mₛₜₐᵣ) can be used as a proxy for the star formation efficiency (SFE=SFR/Mgas), since the two quantities are directly proportional to each other in our regions. In our analysis of both tracers (sSFR and SFE) no significant difference is found the between arm and interarm regions, except for one galaxy (NGC 1097), supporting the gatherers scenario.
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Sun et al. (2025) studied this question.
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