(Proposal ID) S16B-029

(PI) Shibuya, Takatoshi

(Proposal Title)
Spectroscopy for z~5.7 Bright LAEs Selected with First HSC-NB816 Data

(Abstract)
We propose FOCAS and MOIRCS spectroscopy for bright Lyalpha Emitter (LAE) 
candidates at z~5.7 identified with the narrowband (NB) data of the Hyper 
Suprime-Cam (HSC) survey. The survey area reaches ~5 deg^{2} which is ~2.5 
times larger than the previous NB fields for z~5.7 LAEs. By our careful LAE 
selection including the inspections of multi-epoch images for transients 
and moving objects, we identify 7 very rare and bright LAE candidates with 
logL_{Lyalpha}>43.4 erg s^{-1}. We will carry out spectroscopic follow-up 
observations with FOCAS for the 7 LAE candidates through Lyalpha detections. 
In addition, we will perform the MOIRCS spectroscopy for the brightest 4 LAEs 
to investigate whether these objects have signatures of Pop III stars or AGN 
activity based on the C {iv}/Lyalpha and He {ii}/Lyalpha line ratios. 
Exploiting the spectroscopic data of z~6.6 HSC-LAEs in our approved S16A-060N 
program, we will investigate the evolution in the number density of bright 
LAEs with Pop III stars and/or AGNs from z~6.6 to z~5.7, for the first time. 
This first statistical and spectroscopic study with multi-HSC-NB data would 
provide important hints for understanding the formation mechanisms of Pop III 
stars and black holes in high-z bright galaxies, and the processes of cosmic 
reionization.