Volume 461, Number 2, January II 2007
|Page(s)||411 - 421|
|Section||Cosmology (including clusters of galaxies)|
|Published online||12 September 2006|
RASS-SDSS galaxy cluster survey
VI. The dependence of the cluster SFR on the cluster global properties
European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching, Germany e-mail: firstname.lastname@example.org
2 INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
3 Max-Planck-Institut fur extraterrestrische Physik, 85748 Garching, Germany
Accepted: 1 September 2006
We aim at quantifying the relationships between star formation in cluster galaxies and global cluster properties. Using a subsample of 79 nearby clusters from the RASS-SDSS galaxy cluster catalogue of Popesso et al. (2005, A&A, 433, 431), we perform a regression analysis between the cluster integrated star formation rate (), the cluster total stellar mass (), the fractions of star forming (fSF) and blue (fb) galaxies and other cluster global properties, namely its richness (Ngal, i.e. the total number of cluster members within the cluster virial radius, corrected for incompleteness), velocity dispersion (), virial mass (M200), and X-ray luminosity (LX). All cluster global quantities are corrected for projection effects before the analysis. Galaxy s and stellar masses are taken from the catalog of Brinchmann et al. (2004), which is based on SDSS spectra. We only consider galaxies with in our analysis, and exclude AGNs. We find that both and are correlated with all the cluster global quantities. A partial correlation analysis shows that all the correlations are induced by the fundamental one between and Ngal, hence there is no evidence that the cluster properties affect the mean or per galaxy. The relations between and , on the one side, and both Ngal and M200, on the other side, are linear, i.e. we see no evidence that different clusters have different or different per galaxy and per unit mass. The fraction fSF does not depend on any cluster property considered, while fb does depend on LX. We note that a significant fraction of star-forming cluster galaxies are red (~25% of the whole cluster galaxy population). We conclude that the global cluster properties are unable to affect the properties of cluster galaxies, but the presence of the X-ray luminous intra-cluster medium can affect their colors, perhaps through the ram-pressure stripping mechanism.
Key words: galaxies: clusters: general / galaxies: formation
© ESO, 2006
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