SDSS-IV MaNGA: drivers of stellar metallicity in nearby galaxies
Justus Neumann, D. Thomas, Claudia Maraston, Daniel Goddard, Jianhui Lian, Lewis Hill, H. Domínguez Sánchez, Mariangela Bernardi, Berta Margalef-Bentabol, J. K. Barrera-Ballesteros, Dmitry Bizyaev, Nicholas F Boardman, Niv Drory, José G. Fernández-Trincado, Richard R. Lane
Abstract
ABSTRACT The distribution of stellar metallicities within and across galaxies is an excellent relic of the chemical evolution across cosmic time. We present a detailed analysis of spatially resolved stellar populations based on >2.6 million spatial bins from 7439 nearby galaxies in the Sloan Digital Sky Survey-IV (SDSS-IV) Mapping Nearby Galaxies at APO (MaNGA) survey. To account for accurate inclination corrections, we derive an equation for morphology-dependent determination of galaxy inclinations. Our study goes beyond the well-known global mass–metallicity relation and radial metallicity gradients by providing a statistically sound exploration of local relations between stellar metallicity [Z/H], stellar surface mass density Σ⋆, and galactocentric distance in the global mass–morphology plane. We find a significant resolved mass density–metallicity relation $r\Sigma _\star ZR$ for galaxies of all types and masses above $10^{9.8}\, \mathrm{M_\odot }$. Different radial distances make an important contribution to the spread of the relation. Particularly, in low- and intermediate-mass galaxies, we find that at fixed Σ⋆ metallicity increases with radius independently of morphology. For high masses, this radial dependence is only observed in high Σ⋆ regions of spiral galaxies. This result calls for a driver of metallicity, in addition to Σ⋆ that promotes chemical enrichment in the outer parts of galaxies more strongly than in the inner parts. We discuss gas accretion, outflows, recycling, and radial migration as possible scenarios.