(Proposal ID) S14B-026

(PI) Kashikawa Nobunari

(Proposal Title)
 Blowin' in the Galactic Wind: What Did Help Ionizing Photons Escape from Galaxies?

(Abstract)
One of the plausible mechanisms to effectively expel ionizing photons is the 
galactic wind. Expanding bubbles due to galactic outflows are likely to make 
drafty holes through the interstellar medium, allowing Lyman continuum photons 
to leak from the galaxies. However, there have been few observational evidences
 that clearly show the relation between the galactic outflow and the Lyman 
continuum escape fraction. We propose a deep high-resolution IRCS spectroscopy 
with the aid of LGSAO to detect [O iii] emission lines to measure outflow 
strength from bright distant galaxies, whose Lyman continuum photon has been 
securely detected. This is the first attempt to verify a hypothesis that the 
galactic outflow enhances the escape fraction of galaxies. If we found that 
the outflow speed of Lyman continuum emitting galaxies is faster than the 
average of star-forming galaxies at the same redshift, it is a clear 
observational evidence to prove the hypothesis. The dependence of the escape 
fraction on the outflow strength is a key ingredient for theoretical 
prescriptions of galactic wind, which is a fundamental physical process to 
understand the galaxy/IGM chemical evolutions and cosmic reionization.