Stellar mass, not dynamical mass nor gravitational potential, drives the mass-metallicity relationship

Understand

The widely known relation between stellar mass and gas metallicity (mass-metallicity relation, MZR) in galaxies is often ascribed to the higher capability of more massive systems to retain metals against the action of galactic outflows.

• In this scenario the stellar mass would simply be an indirect proxy of the dynamical mass or of the gravitational potential.
• We test this scenario by using a sample of more than one thousand star-forming galaxies from the MaNGA survey for which dynamical masses have been accurately determined.
• By using three different methods (average dispersion, Partial Correlation Coefficients, Random Forest) we unambiguously find that the gas metallicity depends primarily and fundamentally on the stellar mass.