Galaxy Properties in Clusters: Dependence on the Environment.

H. MURIEL

Brasil

Workshop; Diffuse Light in Galaxy Clusters; 2009

IAU

<!-- @page { size: 21cm 29.7cm; margin: 2cm } P { margin-bottom: 0.21cm } --> We investigate the dependece of several galaxy properties on the environment and cluster identification techniques. We select clusters of galaxies from two catalogues based on the SDSS: the ROSAT_SDSS Galaxy Cluster Survey, which is a X-ray selected cluster sample and the MaxBCG Catalogue, in which clusters are optically selected. Based on a volume limited sample of galaxies drawn from the spectroscopic DR5 SDSS, we constructed sub-samples of clusters of galaxies with more than ten members. Scaling relations as well as segregation of galaxy properties as a function of the normalized clustocentric radii are analyzed. The properties of galaxies in clusters are compared with those of field galaxies. Galaxies in X-ray and MaxBCG selected clusters show similar size-luminosity relations. The Faber-Jackson relation for early-type galaxies in clusters is also the same for X-ray selected and MaxBCG clusters. We found that brightest cluster galaxies (BCGs), non-BCGx-early tipe galaxies in clusters and field early-type galaxies show different size-luminosity relations and have different dynamical properties. Using several criteria to classify galaxies into morphological types, we reproduce the well know morphological segregation. The correlation is up to r/r200 1. For the whole range of clustocentric distances, X-ray selected custers present a higher fraction of early type galaxies than MaxBCG clusters. We also found that bright galaxies preferentially inhabit the cluster centers. Median sizes of galaxies, such as the radius that enclose 50% of petrosian flux r50, present a behaviour that also depends on the cluster selection cirteria. For galaxies in X-ray selected clusters, median values of r50 decrease fir r/r200 goes to zero, whereas the opposite is observed for galaxies in the MaxBCG clusters. These different behaviours are mainly due to type galaxies. The results are discussed in terms of the different processes that affect the evolution of galaxies in different environments.