Mass and Environment as Drivers of Galaxy Evolution. Ii. The Quenching of Satellite Galaxies as the Origin of Environmental Effects

Abstract

We extend the phenomenological study of the evolving galaxy population of Peng et al. (2010) to the central/satellite dichotomy in Yang et al. Sloan Digital Sky Survey (SDSS) groups. We find that satellite galaxies are responsible for all the environmental effects in our earlier work. The fraction of centrals that are red does not depend on their environment but only on their stellar masses, whereas that of the satellites depends on both. We define a relative satellite quenching efficiency ε sat , which is the fraction of blue centrals that are quenched upon becoming the satellite of another galaxy. This is shown to be independent of stellar mass, but to depend strongly on local overdensity, δ, ranging between 0.2 and at least 0.8. The red fraction of satellites correlate much better with the local overdensity δ, a measure of location within the group, than with the richness of the group, i.e., dark matter halo mass. This, and the fact that satellite quenching depends on local density and not on either the stellar mass of the galaxy or the dark matter halo mass, gives clues as to the nature of the satellite-quenching process. We furthermore show that the action of mass quenching on satellite galaxies is also independent of the dark matter mass of the parent halo. We then apply the Peng et al. approach to predict the mass functions of central and satellite galaxies, split into passive and active galaxies, and show that these match very well the observed mass functions from SDSS, further strengthening the validity of this phenomenological approach. We highlight the fact that the observed M * is exactly the same for the star-forming centrals and satellites and the observed M * for the star-forming satellites is independent of halo mass above 10 12 M , which emphasizes the universality of the mass-quenching process that we identified in Peng et al. Post-quenching merging modifies the mass function of the central galaxies but can increase the mass of typical centrals by only about 25%.

The influence of the environmental history on quenching star formation in a Λ cold dark matter universe

“…The latter may instead be more strongly influenced by internal quenching processes (as stellar or AGN feedback). This agrees roughly with results by Peng et al (2012) who show that quiescent fractions of low mass galaxies are mainly dependent on den- Figure 10. Mean radial distance versus the 1 Mpc density for satellites in different stellar mass bins (different panels) in observations (symbols) and models (lines with shaded areas).…”

“…These studies also highlight -even if using different density estimators -a strong density dependence of the quiescent satellite fractions at a given stellar mass. In contrast, for the density dependence of quiescent central galaxies, the situation is less clear: Peng et al (2012) and Kovač (2014) find no significant density dependence on top of the stellar mass dependence, while the quiescent fractions of low mass centrals depend, albeit weakly, on density in the study of Woo et al (2013). These differences may be ascribed to different estimators for quiescence (e.g.…”

“…Peng et al 2012;Kovač 2014 andWoo et al 2013). These studies also highlight -even if using different density estimators -a strong density dependence of the quiescent satellite fractions at a given stellar mass.…”

“…The dependence on density is strongest for quiescent low-mass galaxies (see e.g. Peng et al 2012). In Fig.…”

Giant disk galaxies : Where environment trumps mass in galaxy evolution

“…The parent vs. satellite nature of a galaxy (cf. Berlind et al 2005;Tinker et al 2012) is envisioned to be key to explaining some critical observations (Peng et al 2012; Knobel et al 2013). However, disentangling the physics involved is complicated greatly by the different degrees to which environment correlates with various galaxy properties, such as morphology and color (Blanton et al 2003).…”