The FMOS-COSMOS Survey of Star-forming Galaxies at z ∼ 1.6. VI. Redshift and Emission-line Catalog and Basic Properties of Star-forming Galaxies
Résumé
We present a new data release from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS survey, which contains the measurements of spectroscopic redshift and flux of rest-frame optical emission lines (Hα, [N ii], [S ii], Hβ, [O iii]) for 1931 galaxies out of a total of 5484 objects observed over the 1.7 deg 2 COSMOS field. We obtained H-band and J-band medium-resolution (R ∼ 3000) spectra with FMOS mounted on the Subaru telescope, which offers an in-fiber line flux sensitivity limit of ∼ 1 × 10 −17 erg s −1 cm −2 for an on-source exposure time of five hours. The full sample contains the main population of star-forming galaxies at z ∼ 1.6 over the stellar mass range 10 9.5 M * /M 10 11.5 , as well as other subsamples of infrared-luminous galaxies detected by Spitzer and Herschel at the same and lower (z ∼ 0.9) redshifts and X-ray emitting galaxies detected by Chandra. This paper presents an overview of our spectral analyses, a description of the sample characteristics, and a summary of the basic properties of emission-line galaxies. We use the larger sample to redefine the stellar mass-star formation rate relation based on the dust-corrected Hα luminosity, and find that the individual galaxies are better fit with a parametrization including a bending feature at M * ≈ 10 10.2 M , and that the intrinsic scatter increases with M * from 0.19 to 0.37 dex. We also confirm with higher confidence that the massive (M * 10 10.5 M) galaxies are chemically mature as much as local galaxies with the same stellar masses, and that the massive galaxies have lower [S ii]/Hα ratios for their [O iii]/Hβ, as compared to local galaxies, which is indicative of enhancement in ionization parameter.
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