The main galaxy groups from the SDSS data release 5

Abstract

Aims. We investigate the correlations between galaxy properties and environment. Methods. From the main galaxy sample of the SDSS Data Release 5, we have extracted 11 163 groups at the linking length R 0 = 0.2 ×n −1/3 = 1.97 Mpc by the three-dimensional friends-of-friends (FOF) algorithm, wheren is the mean galaxy density, and compare basic properties of member galaxies of main galaxy groups with those of the main galaxy sample and isolated galaxies in each redshift bin.Results. The luminosities and sizes of galaxies are almost independent of environment, but morphologies and colors are correlated with environment-especially galaxy morphologies.

Compact groups of galaxies (CGs) from the SDSS Data Release 6

“…) of CGs is much smaller than that of other group catalogs (Table 1 of Merch'an & Zandivarez [22]), and smaller than that of groups identified by Deng et al [29] (σ = 71 36 kms ). Due to their high densities and low velocity dispersions, such groups may represent an environment where interactions and galaxy mergers are expected to be more prevalent than in loose groups and clusters.…”

“…The mean of two parameters are respectively:R V = 1 82 Mpc,M V = 2 21 × 10 12 M . The mean virial radius of CGs is smaller than that of groups identified by Deng et al [29] (R V = 3 51 Mpc), but larger than that of other group catalogs (Table 1 of Merch'an & Zandivarez [22]). We also note that the mean virial mass of CGs are much smaller than that of other group catalogs (Table 1 of Merch'an & Zandivarez [22]) and groups identified by Deng et al [29] (M V = 1 38 × 10 13 M ).…”

“…The neighbourhood radius R = 1 2 Mpc is apparently smaller than that used by Deng et al [29] for group identification (R = 1 97 Mpc). The selection of this neighbourhood radius mainly depends on two factors: (1) Most candidate CGs do not merge into loose groups and clusters (When the neighbourhood radius is larger, many candidate CGs will be included into loose groups and clusters).…”

“…Berlind et al [27] used a redshift-space friends-of-friends algorithm to identify galaxy groups and clusters in volumelimited samples of the SDSS redshift survey. From the flux-limited Main galaxy sample of the SDSS Data Release 5 [28], Deng et al [29] identified a galaxy group catalog using the algorithm of [30]. The aim of this work is to construct a catalog of compact groups from the Main galaxy sample [31] of the SDSS Data Release 6 [32].…”

Groups of galaxies in the SDSS Data Release 7

“…The next generation of galaxy group catalogues started from the Las Campanas catalogue of groups by Tucker et al (2000) and was followed by the catalogues based on the 2 degree Field Galaxy Redshift Survey (2dFGRS) data releases (Colless et al 2001(Colless et al , 2003 and the Sloan Digital Sky Survey (SDSS) data releases (Early Data Release, Data Release 1-Data Release 7) (Adelman-McCarthy et al 2008). As one of several important results more search algorithms were developed (De Propris et al 2002;Goto et al 2002;Merchán & Zandivarez 2002;Bahcall et al 2003;Lee et al 2004;Eke et al 2004;Merchán & Zandivarez 2005;Yang et al 2005;Einasto et al 2005;Weinmann et al 2006; Full Table 2 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/514/A102 Tago et al 2006;Berlind et al 2006;Deng et al 2007;Yang et al 2007;Tago et al 2008).…”