The chemical properties of star-forming galaxies at z~1.4 revealed with Subaru/FMOS

Kiyoto Yabe

Revealing the history of the chemical enrichment of galaxies is important to understand the past star-formation history of galaxies in an independent way. In the past years, although many efforts have been made aiming to measure the metallicity of galaxies at high redshift, the sample size at z>1 is still limited for the statistical study. Here, we present results from our recent near-infrared spectroscopic surveys conducted with Subaru/FMOS over ~20 deg^2, consisting of ~4,000 galaxies with significant Ha detection at z~1.4, where galaxies in the most active phase of the cosmic history.In this study, we divide our sample into several stellar mass and star-fromation rate (SFR) bins, and measure the gas phase metallicity by using the [NII]6583/Ha emission line ratio of the composite spectra. The resulting mass-metallicity relation at z~1.4 is generally in agreement with previous studies in a similar redshift range. Although no clear dependence of the mass-metallicity relation with star-formation rate is found in our sample at z~1.4, our result at z~1.4 is close to the fundamental metallicity relation at z~0.1 that is extrapolated to the high-SFR regime.Thanks to our large sample in a wide area, we can examine the dependence of galaxy properties on the large-scale environment. We define the environment of our sample by using volume density smoothed in ~50 cMpc scale and also 10th neighboring local surface density. The effect of the field-edge and OH-mask is corrected. We tentatively find that galaxies in the higher-density region generally show the higher metallicity at a fixed stellar mass, which may imply that chemical enrichment is enhanced in the high-density region along the large-scale structure. In this presentation, we discuss the possible interpretation and some caveats in the results.