On the Luminosity Function of Galaxies in Groups in the Sloan Digital Sky Survey

Abstract

Using galaxy groups identified in the Fourth Data Release of the Sloan Digital Sky Survey (SDSS), we compute the luminosity function for several subsamples of galaxies in groups. In all cases, the luminosity functions are well described by Schechter functions, down to the faintest magnitudes we probe, M0.1 r − 5 log(h) ∼ −16. For the general luminosity function of galaxies in groups in the five SDSS bands, we observe that the characteristic magnitude is brighter in ∼ 0.5 magnitudes compared to those obtained for field galaxies by Blanton et al. (2003b). Even when the observed faint end slope is steeper in galaxy groups, it is statistically comparable with the field value. We analyze the dependence of the galaxy luminosity function with system masses finding two clear trends: a continuous brightening of the characteristic magnitude and a steepening of the faint end slope as mass increases. The results in 0.1 g, 0.1 r, 0.1 i and 0.1 z bands show the same behavior. Using the u − r color to split the galaxy sample into red and blue galaxies, we show that the changes observed as a function of the system mass are mainly seen in the red, passively evolving, galaxy population, while the luminosities of blue galaxies remain almost unchanged with mass. Finally, we observe that groups having an important luminosity difference between the two brightest galaxies of a system show a steeper faint end slope than the other groups. Our results can be interpreted in terms of galaxy mergers as the main driving force behind galaxy evolution in groups.

Galaxy morphology, luminosity, and environment in the SDSS DR7

“…However, a direct comparison with the results of Yang et al (2009) is difficult, because the environmental densities have been estimated differently. Zandivarez et al (2006) shows that the local environment (galaxy group mass) is an important factor in galaxy evolution. They show that the faint-end slope is practically constant for the blue cloud galaxies, while for the red sequence galaxies, the faint end is steeper for more massive systems.…”

Groups and clusters of galaxies in the SDSS DR8

“…During the last decade, several group catalogues that use spectroscopic redshifts have been published, either based on the 2dFGRS (Eke et al 2004;Yang et al 2005;Tago et al 2006), or on earlier releases of the SDSS (Einasto et al 2003;Merchán & Zandivarez 2005;Zandivarez et al 2006;Berlind et al 2006;Berlind & SDSS 2009;Yang et al 2007;Koester et al 2007). However, similar algorithms used to compile these catalogues have yielded groups of galaxies with rather different statistical properties.…”

Groups of galaxies in the SDSS Data Release 7

“…Using earlier releases of the SDSS, preliminary catalogues of groups have been obtained (Einasto et al 2003a; Lee et al 2004;Merchán & Zandivarez 2005;Goto 2005;Yang et al 2005;Weinmann et al 2006;Zandivarez et al 2006;Berlind et al 2006;Yang et al 2007). However, similar algorithms used to compile these catalogues yielded groups of galaxies with rather different statistical properties.…”