Using a subsample of 79 nearby clusters from the RASS-SDSS galaxy cluster
catalogue of Popesso et al. (2005a), we perform a regression analysis between
the cluster integrated star formation rate (Sigma_SFR) the cluster total
stellar mass (M_star), the fractions of star forming (f_SF) and blue (f_b)
galaxies and other cluster global properties, namely its richness (N_gal, i.e.
the total number of cluster members within the cluster virial radius), velocity
dispersion (sigma_v), virial mass (M_200), and X-ray luminosity (L_X). All
cluster global quantities are corrected for projection effects before the
analysis. Galaxy SFRs and stellar masses are taken from the catalog of
Brinchmann et al. (2004), which is based on SDSS spectra. We only consider
galaxies with M_r <= -20.25 in our analysis, and exclude AGNs. We find that
both Sigma_SFR and M_star are correlated with all the cluster global
quantities. A partial correlation analysis show that all the correlations are
induced by the fundamental one between Sigma_SFR and N_gal, hence there is no
evidence that the cluster properties affect the mean SFR or M_star per galaxy.
The relations between Sigma_SFR and M_star, on one side, and both N_gal and
M_200, on the other side, are linear, i.e. we see no evidence that different
clusters have different SFR or different M_star per galaxy and per unit mass.
The fraction f_SF does not depend on any cluster property considered, while f_b
does depend on L_X. 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 SF 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.Comment: 14 pages, 12 figures, accepted for publication on A&A; corrected
coefficient in Tab.
