Bibcode
Aguerri, J. A. L.; Sánchez-Janssen, R.; Muñoz-Tuñón, C.
Bibliographical reference
Astronomy and Astrophysics, Volume 471, Issue 1, August III 2007, pp.17-29
Advertised on:
8
2007
Journal
Citations
61
Refereed citations
60
Description
Context: Large surveys such as the Sloan Digital Sky Survey have made
large amounts of spectroscopic and photometric data of galaxies
available, thereby providing important information for studying galaxy
evolution in dense environments. Aims: We have selected a sample
of 88 nearby (z < 0.1) galaxy clusters from the SDSS-DR4 with
redshift information for the cluster members. In particular, we focus on
the galaxy morphological distribution, the velocity dispersion profiles,
and the fraction of blue galaxies in clusters. Methods: Cluster
membership was determined using the available velocity information. We
derived global properties for each cluster, such as their mean
recessional velocity, velocity dispersion, and virial radii. Cluster
galaxies were grouped into two families according to their u-r colours.
Results: The total sample consists of 10 865 galaxies. As
expected, the highest fraction of galaxies (62%) turned out to be
early-type (red) ones, located at smaller distances from the cluster
centre and showing lower velocity dispersions than late-type (blue)
ones. The brightest cluster galaxies are located in the innermost
regions and show the smallest velocity dispersions. Early-type galaxies
also show constant velocity dispersion profiles inside the virial radius
and a mild decline in the outermost regions. In contrast, late-type
galaxies show ever decreasing velocity dispersions profiles. No
correlation has been found between the fraction of blue galaxies and
cluster global properties,such as cluster velocity dispersion or galaxy
concentration. In contrast, we find a correlation between the X-ray
luminosity and the fraction of blue galaxies. Conclusions: These
results indicate that early- and late-type galaxies may have had
different evolutions. Thus, blue galaxies are located in more
anisotropic and radial orbits than early-type ones. Their star formation
seems to be independent of the cluster global properties in low-mass
clusters, but not for the most massive ones. We consider that it is
unlikely that the whole blue population consists of recent arrivals to
the cluster. These observational results suggest that the global
environment could be important for driving the evolution of galaxies in
the most massive cluster (σ > 800 km s-1). However,
the local environment could play a key role in the galaxy evolution for
low-mass clusters.
Table 1 is only available in electronic form at the CDS via anonymous
ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/471/17