(Proposal ID) S16B-074

(PI) Furusawa, Hisanori

(Proposal Title)
Spectroscopy of Very Bright Ly\alpha Emitters at z=6.5 in HSC-NB Wide Fields

(Abstract)
We propose spectroscopy of ten candidates of very bright Lyman-alpha emitters 
(LAEs) (NB0921<23.6) at z=6.5 with FOCAS, to determine their redshifts. 
The candidates are found in a multi-waveband data set with narrow-band NB0921 
photometry, which covers a ~28 sq.deg area, comprising the ongoing Subaru 
Strategic Program and our own survey campaign. The very wide surveyed area enables us to detect possible bright LAEs associated with very large EW> 50-200Angstrom. With the new sample of bright LAEs, we will put a strong constraint on the 
bright-end (L(Lyalpha)>10^{43.5} erg s^{-1}) of the Lyalpha luminosity 
function, to draw a reliable constraint on the H {i} fraction of the 
intergalactic medium. Followup spectroscopy with MOIRCS on a few promising 
candidates that show very large Lyalpha EW will reveal their stellar contents. 
We will investigate existence of a significant contribution from PopIII-like 
populations, and assess contribution of AGNs in those bright high-z LAEs. 
Based on the spectral data, we will also discuss a role of those bright LAEs 
and the PopIII populations in cosmic reionization, as well as physical 
processes in the LAEs, which will give a better feedback to theoretical models 
for high-z galaxies and the first stars.