Issue |
A&A
Volume 460, Number 3, December IV 2006
|
|
---|---|---|
Page(s) | 673 - 679 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20065789 | |
Published online | 13 September 2006 |
Galaxy properties from voids to clusters in the SDSS-DR4
1
INAF – Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Napoli, Italy
2
Dipartimento di Fisica e Astronomia, Universitá di Catania, via S.Sofia 78, 95123 Catania, Italy
3
INAF – , via Moiariello 16, 80131 Napoli, Italy
4
INAF – Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
Received:
9
June
2006
Accepted:
4
August
2006
Aims.We investigate the environmental dependence of galaxy
population properties in a complete volume-limited sample of 91566 galaxies in the redshift range and with
(that is
), selected from the Sloan Digital Sky
Survey (SDSS) Data Release 4 (DR4). Our aim is to search for
systematic variations in the properties of galaxies with the local
galaxy density. In particular, we analyze how the (
) color
index and the morphological type of galaxies (the latter evaluated
through the SDSS Eclass and FracDev parameters) are
related to the environment and to the luminosity of galaxies, in order
to find hints that can be related to the presence of a “void” galaxy
population.
Methods.“Void” galaxies are identified through a highly
selective criterion, which also takes redshift into account and allows
us to exclude from the sample all the galaxies that are not really
close to the center of underdense regions. We study the ()
color distribution for galaxies in different luminosity bins, and we
look for correlations of color with the environment, the luminosity,
and the morphological type of the galaxies.
Results.We find that galaxies
in underdense regions (voids) have lower luminosity () and
are bluer than cluster galaxies. The transition from overdense to
underdense environments is smooth, the fraction of late-type galaxies
decreases, while the fraction of early-type galaxies increases
smoothly from underdense to dense environments.
Conclusions.We do not find any sudden transition in the galaxy properties with density, which, according to a suggestion by Peebles (2001), should mark the transition to a population of “void” galaxies in ΛCDM models. On the contrary, our results suggest a continuity of galaxy properties, from voids to clusters.
Key words: cosmology: large-scale structure of Universe / galaxies: fundamental parameters
© ESO, 2006
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