(Proposal ID) S15A-061

(PI) Matsuoka, Yoshiki

(Proposal Title)
 First spectroscopic identification of HSC-SSP high-z quasar candidates

(Abstract)
High-redshift quasars are an excellent probe of the distant universe. They 
enable observational studies of the early growth of supermassive black holes, 
the cosmic reionization, and the chemical enrichment of host galaxies in a 
complementary way to other types of objects. We are now starting a new ground-
breaking survey for high-redshift (z > 6) quasars using the exquisite imaging 
data provided by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) 
Survey. We expect to probe down to ~2 mag lower-luminous portion (M_{1450} 
< -22 mag) of the luminosity function than did any previous surveys and 
increase the number of known z > 6 quasars by almost an order of magnitude. 
Here we propose a FOCAS spectroscopy of the first two candidates of the 
faintest-known z > 6 quasars, selected from the SSP-S14A data of the COSMOS 
field. The spectra around 6000--10000 Angstrom will be observed to capture 
characteristic features of high-z quasars (or those of contaminating Galactic 
brown dwarfs). We aim to make the first discovery of HSC high-z quasars and 
evaluate the grand strategy of the project. It will be an important milestone 
towards our final goal of better understanding formation and evolution of 
SMBHs and galaxies in the early universe.