The mass-metallicity relation at z ∼ 0.8: Redshift evolution and parameter dependency

The spectra of emission-line galaxies from the extended Baryon Oscillation Spectroscopic Survey of the Sloan Digit Sky Survey (SDSS) are used to study the mass-metallicity relation (MZR) at z ∼ 0.8. The selected sample contains about 180,000 massive star-forming galaxies with 0.6 < z < 1.05 and . The spectra are stacked in bins of different parameters including redshift, stellar mass, star formation rate (SFR), specific star formation rate (sSFR), half-light radius, mass density, and optical color. The average MZR at z ∼ 0.83 has a downward evolution in the MZR from the local to high-redshift universe, which is consistent with previous works. At a specified stellar mass, galaxies with higher SFR/sSFR and larger half-light radius have systematically lower metallicity. This behavior is reversed for galaxies with larger mass density and optical color. Among the above physical parameters, the MZR has the most significant dependency on SFR. Our galaxy sample at 0.6 < z < 1.05 approximately follows the fundamental metallicity relation (FMR) in the local universe, although the sample inhomogeneity and incompleteness might have an effect on our MZR and FMR.