(Proposal ID) S16B-012

(PI) Yamanaka, Satoshi

(Proposal Title)
New method for estimating the LyC escape fraction of high-z galaxies

(Abstract)
This is a proposal for testing the new method proposed by Zackrisson et al.
(2013), which can constrain the Lyman continuum (LyC) escape fraction, f_{esc}.
This newly-proposed method is based on the relation between EW(Hbeta) and the 
UV slope beta which are not affected by the IGM attenuation, and enables us to 
determine f_{esc} even if the targets are in the reionization era. The goal of 
this proposal is to confirm the trend that the low f_{esc} (< 0.5) galaxies 
indeed show the large EW(Hbeta) (> 100 Angstrom in the rest-frame) and that 
the high f_{esc} (> 0.5) galaxies indeed show the low EW(Hbeta) (< 100 Angstrom
in the rest-frame). For this purpose, we target z~3.2 LyC galaxies in which 
one is at z_{spec}=3.245 spectroscopically identified with high f_{esc} and 
others are fourteen objects at z_{phot}~3.2 observed by NB359 narrow band 
filter. Our targets are optimal because they have relatively bright magnitude, 
the bluest observed UV slope and represent the most reliable LyC candidates. 
Thus we propose K-band MOSFIRE spectroscopy with 1 night observation in order 
to determine the redshift by the emission lines such as [OIII] and to measure 
or constrain the Hbeta line flux.