(Proposal ID) S15B-023

(PI) Yoshida, Michitoshi

(Proposal Title)
Spectro-polarimetry survey of starburst superwinds: kinematics of dust outflow

(Abstract)
We propose a deep optical spectropolarimetry survey of the energetic gas 
outflows  - superwinds - associated with six nearby starburst galaxies to 
reveal the kinematics of the galactic-scale dust outflow. The superwind is 
driven by successive supernova explosions and strong stellar winds in the 
starburst region. It has been evident that huge dust (~ 10^{6-7} M_sun) is 
entrained and expelled from the galaxy disk by superwind. However, the fate 
of this dust is quite uncertain because of the lack of suitable probe to study 
the kinematics of dust. The dust in an outflow scatters the strong emission 
from nuclear starburst, we can thus probe the dust motion with respect to the 
galaxy center using polarized emission-lines. Based of this philosophy, we 
conduct a deep spectropolarimetry survey of Halpha in the superwinds of six 
nearby starbursts. We obtain the kinematic information of the dust in the 
circum-nuclear region of the starbursts by this program. Kinematics of the 
dust is crucial to know whether the dust can escape from the galaxy to inter-
galactic space or not. This observation would give important clues to the 
feedback processes in galaxy evolution as well as the dust pollution of 
inter-galactic space and its relationship with starburst phenomenon.