Photometric properties of low-redshift galaxy clusters

grantor: University of TorontoA comprehensive multicolor CCD photometric study has been made for a sample of forty-five low-redshift (0.04 $\leq$ z $\leq$ 0.18) rich clusters of galaxies, in order to compare many of the properties associated with clusters. Accurate photometric measurements in R, B and I were generated, to sufficiently faint levels, allowing the contribution of dwarf galaxies to be considered. In thesis we have investigated the color magnitude relation for early type galaxies. Our results are consistent with population synthesis models that explain the CMR as an effect produced by varying metallicities and passive evolution. The universality of the CMR slope is established, and rules out any major star formation activity in cluster early-type galaxies during the last 11 Gyr. Color information is used as an additional constraint in generating the luminosity function (LF) of cluster galaxies. The analysis of the whole sample reveals that the characteristic magnitude of cD clusters varies with richness. Non-cD clusters present small variations that are consistent with the hypothesis of universality of their LF. 100% completeness is reached in the range of absolute magnitude between $M\sb{R}$ = $-$25 and $M\sb{R}$ = $-$17($H\sb{o}$ = 50 km s$\sp{-1}$Mpc$\sp{-1};q\sb{o}$ = 0) in a subsample of twenty-two clusters. Some evidence has been found to indicate that cD clusters have depleted a large number of dwarf galaxies. Based on these results, an alternative scenario for cD galaxy formation has been proposed.Ph.D