MOIRCS DEEP SURVEY. VIII. EVOLUTION OF STAR FORMATION ACTIVITY AS A FUNCTION OF STELLAR MASS IN GALAXIES SINCEz∼ 3

We study the evolution of star formation activity of galaxies at 0. 5~1. We found galaxies at 2. 51 and becomes significant at z~3, especially in the case with the SFR based on MIPS 24um. In galaxies with Mstar = 10^10-11. 5 Msun, those with a relatively narrow range of SSFR (<~1 dex) dominates the cosmic SFRD at 0. 5<z<3. 5. The SSFR of galaxies which dominate the SFRD systematically increases with redshift. At 2. 5<z<3. 5, the high-SSFR population, which is relatively small in number, dominates the SFRD. Major star formation in the universe at higher redshift seems to be associated with a more rapid growth of stellar mass of galaxies.