(Proposal ID) S15A-124

(PI) Hayashi, Masao

(Proposal Title)
 Definitive Measurements of the Mass-Metallicity-SFR Relation at z~2.2

(Abstract)
We propose for FMOS spectroscopy of ~90 Halpha-selected galaxies at z=2.2 to 
capture [O ii], Hbeta, and [O iii]. Our primary objective is to compute gas 
metallicities and determine its relationship with SFR and stellar mass, during 
a critical period in galaxy evolution where star formation was at its global 
maximum. The study will reveal how the relative importance of the physical 
processes driving metal enrichment, star formation, and stellar feedback may 
have changed over cosmic time. Unlike previous high-z studies that derive 
luminosity-weighted gas metallicity from stacked spectra, our program will 
obtain robust gas metallicity measurements for ~30 individual galaxies, a 
factor of ~4 over current samples. FMOS is the ideal instrument for obtaining 
near-IR spectroscopy for our sample: the areal coverage, number densities, and 
depths of our Halpha sample are excellent matches to FMOS' FoV, fiber density 
and sensitivity. In addition, the emission lines of our galaxies have been pre-
selected to fall in clean OH windows. The powerful combination of FMOS and 
narrowband imaging will yield a dataset which addresses critical limitations 
of previous high-z metallicity studies. These observations will also allow us 
to determine if massive stars or an AGN dominate the emission-line luminosity 
at z=2.2.