邀请团队:　2.4米望远镜组

摘要:　　　In the hierarchical structure formation paradigm, galaxies and galactic structures are formed through merging of smaller galaxies/structures. In this theory, major mergers (mergers with mass ratios less than 3) play significant roles. Important debates are currently going on regarding to the evolution of merger rate and to the contribution of mergers to galaxy assembly. A major reason for the controversies is due to sample selection effects. We have designed a set of major merger selection criteria which minimize the known biases and can be applied equally to galaxies of low and high redshifts. In this talk I will present two recent papers using major-merger samples so selected. The first is on the specific star formation (sSFR) enhancement in z=0 mergers, based on Spitzer observations of a K-band selected sample of local major-merger pairs. The second paper, using a mass selected major-merger pairs sample in the COSMOS field, studies the merger rate evolution since z=1 and the contribution of mergers to the mass growth of galaxies and to the formation of elliptical galaxies and red quiescent galaxies (RQGs).