How does galaxy environment matter? The relationship between galaxy environments, colour and stellar mass at 0.4 < z < 1 in the Palomar/DEEP2 survey

Abstract

We present a study characterizing the environments of galaxies in the redshift range of 0.4 < z < 1 based on data from the POWIR near‐infrared imaging and DEEP2 spectroscopic redshift surveys, down to a stellar mass of log M*= 10.25 M⊙. Galaxy environments are measured in terms of nearest‐neighbour densities as well as fixed aperture densities and kinematical and dynamical parameters of neighbour galaxies within a radius of 1 h−1 Mpc. We disentangle the correlations between galaxy stellar mass, galaxy colour and galaxy environment, using not only galaxy number densities, but also other environmental characteristics such as velocity dispersion, mean harmonic radius and crossing time. We find that galaxy colour and the fraction of blue galaxies depends very strongly on stellar mass at 0.4 < z < 1, while a weak additional dependence on local number densities is in place at lower redshifts (0.4 < z < 0.7). This environmental influence is most visible in the colours of intermediate‐mass galaxies (10.5 < log M* < 11), whereas colours of lower‐ and higher‐mass galaxies remain largely unchanged with redshift and environment. At a fixed stellar mass, the colour–density relation almost disappears, while the colour–stellar mass relation is present at all local densities. We find a weak correlation between stellar mass and environment at intermediate redshifts, which contributes to the overall colour–density relation. We furthermore do not find a significant correlation between galaxy colour and virial mass, i.e. parent dark matter halo mass. Galaxy stellar mass thus appears to be the crucial defining parameter for intrinsic galaxy properties such as ongoing star formation and colour.

Nature vs. nurture in the low-density environment: structure and evolution of early-type dwarf galaxies in poor groups

“…This scenario is in agreement with findings based on large redshift surveys, which revealed an increasing environmental effect on galaxy evolution moving from higher to lower redshift, and from higher to lower galaxy stellar masses (Iovino et al 2010;Peng et al 2010;Grützbauch et al 2010).…”

“…They can suffer from tidal truncation (e.g., Rubin et al 1988) or tidal disruption (e.g., Oh et al 1995) during their orbit through a more massive dark matter halo, like a group or cluster of galaxies. Indeed, studies of the environmental influence on galaxy properties have found that the correlations between colour or star formation rate (SFR) and local galaxy density are the strongest for low-mass galaxies (Kauffmann et al 2004;Tasca et al 2009;Grützbauch et al 2010). Similarly, the morphology-density relation is very strong for low-mass galaxies (e.g., Binggeli et al 1990).…”

A journey from the outskirts to the cores of groups

“…It is widely accepted in the literature that classical galaxy color/morphology trends in different environments are better investigated in bins of mass-volume-limited samples (Tasca et al 2009;Iovino et al 2010;Cucciati et al 2010;Kovač et al 2010;Xue et al 2010;Cooper et al 2010;Grützbauch et al 2011). This strategy enables one to break the degeneracy caused by the relationships between galaxy stellar masses and environment and between galaxy stellar masses and colors/morphologies.…”

Galaxy-galaxy lensing constraints on the relation between baryons and dark matter in galaxies in the Red Sequence Cluster Survey 2

“…The stellar mass estimates are tightly correlated to various other important global properties of galaxies (colour, metallicity, luminosity, environment, see e.g. Grützbauch et al 2011, and references therein) and they are therefore considered a useful tracer of the baryonic content of a galaxy.…”