The mass-metallicity relation at z~1.4 revealed with Subaru/FMOS
  We present a stellar mass-metallicity relation at z~1.4 with an
unprecedentedly large sample of ~340 star-forming galaxies obtained with FMOS
on the Subaru Telescope. We observed K-band selected galaxies at 1.2 < z_{ph} <
1.6 in the SXDS/UDS fields with M_{*} > 10^{9.5} M_{\sun}, and expected
F(H\alpha) > 5 \times 10^{-17} erg s^{-1} cm^{-2}. Among the observed ~1200
targets, 343 objects show significant H\alpha emission lines. The gas-phase
metallicity is obtained from [NII]\lambda 6584/H\alpha line ratio, after
excluding possible active galactic nuclei (AGNs). Due to the faintness of the
[NII]\lambda 6584 lines, we apply the stacking analysis and derive the
mass-metallicity relation at z~1.4. Our results are compared to past results at
different redshifts in the literature. The mass-metallicity relation at z~1.4
is located between those at z~0.8 and z~2.2; it is found that the metallicity
increases with decreasing redshift from z~3 to z~0 at fixed stellar mass.
Thanks to the large size of the sample, we can study the dependence of the
mass-metallicity relation on various galaxy physical properties. The average
metallicity from the stacked spectra is close to the local FMR in the higher
metallicity part but >0.1 dex higher in metallicity than the FMR in the lower
metallicity part. We find that galaxies with larger E(B-V), B-R, and R-H
colours tend to show higher metallicity by ~0.05 dex at fixed stellar mass. We
also find relatively clearer size dependence that objects with smaller half
light radius tend to show higher metallicity by ~0.1 dex at fixed stellar mass,
especially in the low mass part.
