SIGNALS on the mixing of oxygen and nitrogen in the spiral galaxy NGC 6946 Bresolin, Fabio Zurita Muñoz, Almudena Duarte Puertas, Salvador HII regions galaxies: abundances galaxies: individual: NGC 6946 galaxies: ISM galaxies: spiral Based on observations obtained with SITELLE, a joint project between Université Laval, ABB-Bomem, Université de Montréal, and the CFHT with funding support from the Canada Foundation for Innovation (CFI), the National Sciences and Engineering Research Council of Canada (NSERC), Fond de Recherche du Québec – Nature et Technologies (FRQNT), and CFHT. DF-A acknowledges the support from the National Science Foundation under grant 2109124 for SIGNALS: Unveiling Star-Forming Regions in Nearby Galaxies. LR-N is grateful to the National Science Foundation (NSF) – 2109124, the Dunlap Institute, and the Natural Sciences and Engineering Research Council of Canada (NSERC) – RGPIN-2023-03487 for their support. The Dunlap Institute was funded through an endowment established by the David Dunlap family and the University of Toronto. AZ acknowledges support from projects PID2023-150178NB-I00 and PID2020-114414GB-I00, financed by MCIN/AEI/10.13039/501100011033 and from the Junta de Andalucía (Spain) local government through the FQM-108 project. CR and LD are thankful for a FRQNT-SIGNALS team grant and NSERC-Discovery grants. As part of the SIGNALS (Star formation, Ionized Gas, and Nebular Abundances Legacy Survey) survey, which comprises a sample of approximately 40 nearby galaxies observed with the Fourier transform spectrometer SITELLE, we present a study of metal mixing in the spiral galaxy NGC 6946. Taking advantage of the blue sensitivity of our set-up, we measure the oxygen and nitrogen abundances of 638 H ii regions, and focus our analysis on the abundance fluctuations about the radial gradients. We detect an azimuthal variation of about 0.1 dex in these abundances across the north-east spiral arm, with the leading edge being more metal-poor than the trailing edge. This result aligns with galaxy simulations, where radial gas flows along the spiral arms lead to dilution on the leading edge and enrichment on the trailing edge, due to the presence of radial metallicity gradients. Our 2D analysis reveals that oxygen and nitrogen exhibit comparable spatial correlation scales, despite the different injection energies and distinct nucleosynthetic origins – core-collapse supernovae in the case of oxygen and primarily asymptotic giant branch stars for nitrogen. The observed similarity suggests that stellar processes drive these two elements into the interstellar medium over equivalent spatial scales. 2025-04-24T09:03:35Z 2025-04-24T09:03:35Z 2025-03-28 journal article F. Bresolin et al. SIGNALS on the mixing of oxygen and nitrogen in the spiral galaxy NGC 6946. 2025, MNRAS, Volume 539, Issue 2, Pages 755–770, https://doi.org/10.1093/mnras/staf510 https://hdl.handle.net/10481/103779 10.1093/mnras/staf510 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Oxford University Press