YOUNG, STAR-FORMING GALAXIES and THEIR LOCAL COUNTERPARTS: The EVOLVING RELATIONSHIP of MASS-SFR-METALLICITY since z ∼ 2.1

We explore the evolution of the Stellar Mass-Star Formation Rate (SFR)-Metallicity relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90 < z < 2.35. We present the galaxies' rest-frame optical emission-line fluxes derived from IR-grism spectroscopy with the Hubble Space Telescope and combine these data with SFRs and stellar masses obtained from deep, multi-wavelength (rest-frame UV to IR) photometry. We then compare these measurements to those for a local sample of galaxies carefully matched in stellar mass () and SFR ( in M_o yr^-1). We find that the distribution of z ∼ 2.1 galaxies in stellar mass-SFR-metallicity space is clearly different from that derived for our sample of similarly bright ( erg s^-1) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above and SFRs above yr^-1, the z ∼ 2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.