The Statistical Properties of Galaxy Morphological Types in Compact Groups of Main Galaxies From the SDSS Data Release 4

Abstract

In order to explore the statistical properties of galaxy morphological types in compact groups (CGs), we construct a random group sample which has the same distributions of redshift and number of member galaxies as those of the CG sample. It turns out that the proportion of early-type galaxies in different redshift bins for the CG sample is statistically higher than that for random group sample, and with growing redshift z this kind of difference becomes more significant. This may be due to the existence of interactions and mergers within a significant fraction of SDSS CGs. We also compare statistical results of CGs with those of more compact groups and pairs, but do not observe as large statistical difference as Hickson's [Astrophys. J. 255 (1982) 382] results.

The main galaxy groups from the SDSS data release 5

“…This shows that the luminosity is not strongly correlated with environment. A similar conclusion was obtained by Deng et al (2007). They compared statistical properties of galaxy luminosity in a compact galaxy group sample with those in a random group sample, and found that the two samples had the same statistical properties of luminosity.…”

“…clusters or groups) have a high proportion of early type morphologies (e.g. Oemler 1974;Dressler 1980;Whitmore et al 1993;Deng et al 2007) and low SFRs (e.g. Balogh et al 1997Poggianti et al 1999).…”

“…clusters or groups) have predominantly early type morphologies (e.g. Oemler 1974;Dressler 1980;Whitmore et al 1993;Deng et al 2007), while galaxies in the lowest density regions (isolated galaxies) have a lower proportion of early-type galaxies (e.g. Deng et al 2006b).…”

The local environmental dependence of properties of Luminous Red Galaxies (LRGs) from the SDSS data release 6 (SDSS6)

“…It is widely accepted that galaxy morphologies strongly depend on local environment: galaxies in dense environments (i.e., clusters or groups) have a higher proportion of early-type morphologies [1][2][3][4], while galaxies in the lowest density regions (isolated galaxies) have a lower proportion of early-type galaxies [55]. Deng et al [43] also found that galaxy morphologies strongly depend on local environment.…”

“…Numerous studies have shown that galaxy properties seem to correlate (significantly) with environment, for example, galaxies in dense environments (i.e., clusters or groups) have a higher proportion of early type morphologies [1][2][3][4] and low SFRs [5][6][7]. Many authors have investigated the correlations between environment and galaxy properties, such as those between environment and morphology [8][9][10][11][12][13][14][15][16][17], those between environment and star formation rate [18][19][20][21][22][23][24], and those between environment and color [17,23,[25][26][27][28][29].…”