Stellar mass-metallicity relation. I.

The lower limit of our stellar mass range is M*=10^9.7^M_{sun}_, the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We report a detection of an evolution of the stellar MZR with observed redshift at 0.037+/-0.007dex per Gyr, consistent with the predictions from hydrodynamical simulations.

Additionally, we find that the evolution of the stellar MZR with observed redshift can be explained by an evolution of the stellar MZR with the formation time of galaxies, i.e., when the single stellar population (SSP)-equivalent ages of galaxies are taken into account. This behavior is consistent with stars forming out of gas that also has an MZR with a normalization that decreases with redshift. Lastly, we find that over the observed mass range, the MZR can be described by a linear function with a shallow slope ([Fe/H]{propto}(0.16+/-0.03)logM*).