The Star Formation Properties For The Galaxy Clusters

To study the star formation history of the universe is one of the major tasks of extragalactic astronomy. The current star formation rates (SFRs) of galaxies and the variation with morphology environment and some physical properties of galaxies are crucial in our understanding of the evolution of galaxies.The merging cluster of galaxies A2255 is covered by the Sloan Digital Sky Survey (SDSS). The physical parameters of 184 bright member galaxies derived from the SDSS data analyses by Brinchmann et al. allow a detailed study on the star formation properties of the galaxies within a merging cluster at intermediate redshift. In this thesis we perform a morphological classification on the basis of the SDSS imaging and spectral data, and investigate the morphological dependence of the star formation rates (SFRs) for these member galaxies. Additionally, the SFR variation with the projected radial distance are found to be heavily dependent upon galaxy morphology: the early-type galaxies have a very weak inner decrease in SFR/M_* while the inner late-type galaxies tend to have higher SFR/M_*, values than the outer late-types.Rich cluster hosting only one central cD galaxy represents a class of galaxy clusters at the end stage of virialization. For a better understanding of the relation between star-formation properties of galaxies and dynamics of their parent clusters, we also study the star formation properties of 369 bright galaxies in three cD clusters of galaxies A1767, A1809, and A2670. Additionally, we update the peculiar velocities of the central cD galaxies with respect to bulk receding velocities of clusters. The early- and late-type galaxies in these three cD clusters are found to follow the same trend that the galaxies in inner/denser regions have lower normalized star formation rates (SFRs) by stellar mass (SFR/M_*), which can be interpreted by a significant SFR suppression when the galaxies enter the dense environment. Compared with the merging cluster A2255, the star formation history for the late-type cluster galaxies is likely closely related to the virialization stage of parent cluster. This also may suggest that the galaxy-scale turbulence stimulated by the merging of subclusters might have played a key role on the star formation...