(Proposal ID) S15B-059

(PI) Yuma, Suraphong

(Proposal Title)
Follow-up FOCAS Spectroscopy for [O iii] Blobs at z~0.7

(Abstract)
{This proposal is the continuation of the program approved in S14B-130.} We 
propose to complete FOCAS spectroscopy for seven [O{iii}] blobs at z~0.7, 
three of which are observed in S14B-130 but with bad weather. All blobs show 
remarkably extended [O{iii}] emission larger than 30 kpc down to 1.2x10^{-18} 
ergs^{-1}cm^{-2} arcsec^{-2} beyond their stellar component, which is thought 
to be hot metal-rich gas outflowing from galaxies. However, without 
spectroscopy to verify gas motion of the system, we cannot certainly conclude 
that the extended feature of [O{iii}] emission is caused by gas outflow. We 
will 1) confirm the outflow of these blobs through Fe{ii} and/or Mg{ii} 
absorption lines, 2) constrain energy source of the outflow (AGN or stellar 
feedback) through line-ratio diagnostic diagram, and 3) investigate if the 
extended oxygen emission is photo-ionized outflowing gas or involving shock 
excitation through [O{ii}]/[O{iii}] ratios in extended regions. By our 
previous FOCAS observations, we successfully confirm the outflow signature 
in one blob and determine their energy source and ionization state. With 
additional observing time, we will be able to significantly improve the 
statistics (from one to eight blobs), and probe different phase of large-scale 
outflowing gas that might lead to the star formation quenching.