アブストラクト：
"As a formation mechanism of giant clumps in star-forming galaxies at high redshifts, two processes are proposed: the violent disk instability and galaxy mergers. Since these processes seem to depend on density environments of galaxies, it is expected that fractions of clumpy galaxies vary with environments. We investigate the fractions of star-forming galaxies with multiple components at z=2-2.5 in two different environments using the HST/ACS+WFC3 imaging data. We find that the fractions of clumpy galaxies do not show a strong environmental dependence at z~2. In this talk, I would like to show our results and discuss how we can interpret the results. "