Issue |
A&A
Volume 439, Number 1, August III 2005
|
|
---|---|---|
Page(s) | 45 - 58 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20042347 | |
Published online | 22 July 2005 |
Toward understanding environmental effects in SDSS clusters
1
Tartu Observatory, 61602 Tõravere, Estonia e-mail: einasto@aai.ee
2
Tuorla Observatory, Väisäläntie 20, Piikkiö, Finland
3
Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str 1, 86740 Garching, FRG, Germany
4
Fermi National Accelerator Laboratory, MS 127, PO Box 500, Batavia, IL 60510, USA
Received:
9
November
2004
Accepted:
5
April
2005
We find groups and clusters of galaxies using the Data
Releases DR1 and DR3 of the Sloan Digital Sky Survey. We calculate a
low-resolution density field with a smoothing length of 10 h-1 Mpc to
characterise the density of the cluster environment, and a
medium-resolution density field with a smoothing length of 2 h-1 Mpc to
characterise the galaxy environment. We determine the luminosity
function of clusters, and investigate properties of galaxies and
clusters in various environments. We show that clusters in a
high-density environment are about 5 times more luminous
than in a low-density environment, and luminosities
of galaxies in different environments differ by a factor of ∼25.
We see similar effects in
numerical simulations – simulated clusters in a high-density
environment are ~ times more massive than those in a low-density
environment. Comparison of the density distribution in simulations at
various epochs shows that in large low-density regions
(voids) dynamical evolution is very slow and stops early.
In contrast, in large regions of higher density (superclusters)
dynamical evolution starts early and continues until the present; here
particles cluster early, and by merging of smaller groups very rich
systems of galaxies form.
Key words: large-scale structure of Universe / galaxies: clusters: general / dark matter
© ESO, 2005
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