(Proposal ID) S16A-058

(PI) Suzuki, Tomoko

(Proposal Title)
The ISM properties of z>3 [OIII] emitters and their environmental dependence

(Abstract)
Recent near-infrared spectroscopic observations are revealing the different 
physical conditions between high-z and low-z star-forming galaxies. Our team 
has been conducting spectroscopic surveys for star-forming galaxies in high 
density regions at z~2 and discussing their inter stellar medium (ISM) 
conditions by comparing with field galaxy samples. We now try to expand our 
targets to higher redshifts, z>3. Using the public narrow-band survey data by 
HiZELS, we construct a sample of [Oiii] emission line galaxies at z=3.24 in 
the COSMOS field, and find an over-density region of the [Oiii] emitters. We 
here propose deep spectroscopy with MOSFIRE/Keck for the active galaxies in 
the over-density region at z>3. We aim to detect the multiple lines, [Oii], 
Hbeta, and [Oiii], for individual galaxies, and to characterize their ISM 
properties by measuring the ionization parameters and metallicities. By 
comparing our [Oiii] emitter sample with the field galaxy samples at the same 
epoch but in the different environments, we will discuss the environmental 
dependence of the ISM properties of star-forming galaxies before the peak 
epoch of galaxy formation for the first time.