(Proposal ID) S14A-020

(PI) Tadaki Ken-ichi

(Proposal Title)
 Constraints on bulge and disk formation scenarios in clumpy disks

(Abstract)
Recent observations suggest that bulges form in lockstep with disks for Milky-
Way-like galaxies to z ~ 1, which rules out the inside-out growth. Our goal is 
to validate the physical processes of such lockstep evolution of bulges and 
disks as suggested by the simulations: bulge formation by clump migration and 
disk formation by clump disruption. To derive the key properties such as "age 
and dynamical mass of clumps", "tidal force of host galaxies" and "mass loss 
rate by outflow", we propose Paalpha integral field spectroscopic observations 
of a starbursting galaxy at z = 0.13 in COSMOS field with NIFS and LGS on 
Gemini. The target has a clumpy structure and have enhanced SFRs compared to 
local typical star-forming galaxies and rather resemble high-z galaxies in 
many respects, suggesting it would be just in the formation phase of bulges 
and disks. Since the size of such giant clumps is known to be 0.5-1.0 kpc, 
corresponding to 0.2-0.4 arcsec at z = 0.13, the high resolution and high 
sensitivity observations with AO are key to measure the clump properties. The 
proposed observations provide us with the crucial information for constraints 
on the bulge and disk formation scenarios, and are an important step for a 
future survey with TMT, targeting clumpy galaxies at z = 1 - 2.