MAUVE-MUSE: When Metallicity Follows or Fights Star Formation -- A Mass-Dependent Inversion in Virgo Galaxies

Abstract

Although globally-integrated studies often find that, at fixed stellar mass, high star formation rate (SFR) galaxies are relatively metal-poor while lower-SFR systems are more metal-rich, the corresponding coupling between gas-phase metallicity ($Z_{\mathrm{gas}}$) and star formation on sub-galactic scales remains poorly constrained. In this study, we analyse 14 Virgo spirals from the MAUVE-MUSE survey to revisit the resolved mass-metallicity relation (rMZR) and its secondary dependence on SFR surface density (${\Sigma }_{\mathrm{SFR}}$) at $\sim 100$\,pc scales. We construct co-spatial maps of stellar mass surface density (${\Sigma }_{\ast }$), ${\Sigma }_{\mathrm{SFR}}$, and oxygen abundance. MAUVE-MUSE galaxies follow a standard rMZR, but when binned by ${\Sigma }_{\ast }$, we find a mass-dependent inversion in the $Z_{\mathrm{gas}}$-${\Sigma }_{\mathrm{SFR}}$ relation using O3N2 calibrations: the standard anti-correlation is confined to low-${\Sigma }_{\ast }$ bins, while high-${\Sigma }_{\ast }$ regions show a positive correlation, inverting at ${\log }_{10}({\Sigma }_{\ast }/M_{\odot }{\mathrm{kpc}}^{-2})\simeq 7.5$-8.0. Correlated and anti-correlated \ion{H}{ii} regions coexist within the same discs; the mass dependence emerges only when grouping spaxels by ${\Sigma }_{\ast }$. We develop a spatially resolved gas-regulator model showing this $Z_{\mathrm{gas}}$-${\Sigma }_{\mathrm{SFR}}$ (anti-)correlation arises from competition between star-formation-driven and gas-supply-driven variability. This framework naturally extrapolates to the integrated scenario, providing a unified explanation for resolved and global relations. However, the presence and strength of the $Z_{\mathrm{gas}}$-${\Sigma }_{\mathrm{SFR}}$ (anti-)correlation depend strongly on the metallicity indicator used, highlighting the challenge of disentangling physical secondary trends within metallicity scaling relations.

20 pages, 7 figues, accepted by MNRAS