(Proposal ID) S15B-030

(PI) Murata, Katsuhiro

(Proposal Title)
FMOS Follow-up Survey for Clumpy Galaxies at z~0.8 in COSMOS

(Abstract)
Many star-forming galaxies at z>1 have irregular shapes with giant star-
forming clumps. They are considered to be progenitors of normal (disk) 
galaxies at low redshifts. Therefore it is important to study the evolution 
of these clumpy galaxies in order to understand the formation process of 
normal galaxies in the present universe. We systematically searched clumpy 
galaxies in the COSMOS 2 deg^2 field and found that the fraction of clumpy 
galaxies strongly depends on the SSFR but not on the stellar mass. While it 
may indicate that the SSFR is fundamental physical parameter for the origin 
of the clumpy galaxies, the SSFRs estimated from the SED fitting technique 
tend to have relatively large uncertainty. We propose a NIR spectroscopic 
follow-up observation for clumpy galaxies at 0.7<z<1.0 in the COSMOS field 
with Subaru/FMOS in order to measure their Halpha and [N{II}]lambda6584 
emission-line fluxes. Our immediate objectives are 1) to estimate their 
EW(Halpha) and investigate how the fraction of clumpy galaxies depends on 
EW(Halpha), 2) to measure SFRs from the Halpha fluxes and estimate their 
gas mass from the surface SFR density, and 3) to estimate the gas metallicity 
from the [N{II}]/Halpha ratio and compare the mass-metallicity relation 
between clumpy galaxies and normal galaxies.