Galaxy Properties in Clusters: Dependence on the Environment and the Cluster Identification Techniques

V. COENDA & H. MURIEL

ASTRONOMY AND ASTROPHYSICS

Año: 2009 vol. 504 p. 347 - 358

0004-6361

We investigate the dependence of several galaxy properties on the environmentand cluster identification techniques. We select clusters of galaxies from twocatalogues based on the SDSS: the ROSAT-SDSS Galaxy Cluster Survey, and theMaxBCG Catalogue. Based on a volume limited sample of galaxies drawn from thespectroscopic DR5 SDSS, we constructed sub-samples of clusters of galaxies withmore than ten members. Scaling relations as well as segregation of galaxyproperties as a function of the normalized clustocentric radii are analyzed.The properties of galaxies in clusters are compared with those of fieldgalaxies. Galaxies in X-ray and MaxBCG selected clusters show similarsize-luminosity relations. At equal luminosity, late type galaxies in the fieldhave sizes smaller than cluster galaxies of the same morphological type. TheFaber-Jackson relation for early-type galaxies in clusters is also the same forX-ray selected and MaxBCG clusters. We found clear differences between thedynamical properties of galaxies in clusters, the brightest cluster galaxies($BCG_s$) and field galaxies. Using several criteria to classify galaxies intomorphological types, we reproduce the well know morphological segregation. Thecorrelation is up to $r/r_{200} sim 1$. For the whole range of clustocentricdistances, X-ray selected clusters present a higher fraction of early typegalaxies than MaxBCG clusters. We also found that bright galaxiespreferentially inhabit the cluster centers. Median sizes of galaxies, such asthe radius that enclose $50%$ of petrosian flux $r_{50}$, present a behaviourthat also depends on the cluster selection criteria. The resultsare discussedin terms of the different processes that affect the evolution of galaxies indifferent environments.