SDSS-IV MaNGA: galaxy gas-phase metallicity gradients vary across the mass-size plane

Gas-phase abundances and abundance gradients provide much information on past stellar generations, and are powerful probes of how galaxies evolve. Gas abundance gradients in galaxies have been studied as functions of galaxies' mass and size individually, but have largely not been considered across the galaxy mass-size plane. Thus, we investigate gas-phase abundance gradients across this plane, using a sample of over 1000 galaxies selected from the MApping Nearby Galaxies at APO (MaNGA) spectroscopic survey. We find that gradients vary systematically such that above 10(10) M-circle dot, smaller galaxies display flatter gradients than larger galaxies at a given stellar mass. This mass-size behaviour cannot be explained by instrumental effects, nor is it simply a reflection of known trends between gradients and morphology. We explore multiple possibilities for a physical origin for this pattern, though further work is needed to establish a firm physical interpretation.

Automated summary

Gas-phase abundance gradients in galaxies have been found to vary systematically with galaxy size and mass, with smaller galaxies displaying flatter gradients than larger galaxies at a given stellar mass above 10^10 solar masses. This mass-size behavior cannot be explained by instrumental effects, and is not simply a reflection of known trends between gradients and morphology. Further investigation is needed to establish a firm physical interpretation for this pattern.