THE METALLICITY EVOLUTION OF STAR-FORMING GALAXIES FROM REDSHIFT 0 TO 3: COMBINING MAGNITUDE-LIMITED SURVEY WITH GRAVITATIONAL LENSING

We present a comprehensive observational study of the gas-phase metallicity of star-forming galaxies from z similar to 0 -> 3. We combine our new sample of gravitationally lensed galaxies with existing lensed and non-lensed samples to conduct a large investigation into the mass-metallicity (MZ) relation at z > 1. We apply a self-consistent metallicity calibration scheme to investigate the metallicity evolution of star-forming galaxies as a function of redshift. The lensing magnification ensures that our sample spans an unprecedented range of stellar mass (3 x 10(7) to 6 x 10(10) M-circle dot). We find that at the median redshift of z = 2.07, the median metallicity of the lensed sample is 0.35 dex lower than the local SDSS star-forming galaxies and 0.18 dex lower than the z similar to 0.8 DEEP2 galaxies. We also present the z similar to 2 MZ relation using 19 lensed galaxies. A more rapid evolution is seen between z similar to 1 -> 3 than z similar to 0 -> 1 for the high-mass galaxies (10(9.5)M similar to < M-* < 10(11) M-circle dot), with almost twice as much enrichment between z similar to 1 -> 3 than between z similar to 1 -> 0. We compare this evolution with the most recent cosmological hydrodynamic simulations with momentum-driven winds. We find that the model metallicity is consistent with the observed metallicity within the observational error for the low-mass bins. However, for higher masses, the model overpredicts the metallicity at all redshifts. The overprediction is most significant in the highest mass bin of 10(10)-10(11) M-circle dot.