The stellar mass content of distant galaxy groups

Abstract

We have obtained near-infrared imaging of 58 galaxy groups, in the redshift range 0.1<z<0.6, from the William Herschel Telescope and from the Spitzer IRAC data archive. The groups are selected from the CNOC2 redshift survey, with additional spectroscopy from the Baade telescope (Magellan). Our group samples are statistically complete to K(Vega}=17.7 (INGRID) and [3.6](AB)=19.9 (IRAC). From these data we construct near-infrared luminosity functions, for groups in bins of velocity dispersion, up to 800 km/s, and redshift. The total amount of near-infrared luminosity per group is compared with the dynamical mass, estimated from the velocity dispersion, to compute the mass-to-light ratio, M/Lk. We find that the M/Lk values in these groups are in good agreement with those of their statistical descendants at z=0, with no evidence for evolution beyond that expected for a passively evolving population. There is a trend of M/Lk with group mass, which increases from M/Lk~10 for groups with sigma<250 km/s to M/Lk~100 for sigma=425-800 km/s. This trend is weaker, but still present, if we estimate the total mass from weak lensing measurements. In terms of stellar mass, stars make up ~2 per cent of the mass in the smallest groups, and ~1 per cent in the most massive groups. We also use the near-infrared data to consider the correlations between stellar populations and stellar masses, for group and field galaxies at 0.1<z<0.6. We find that fewer group galaxies show strong [OII] emission compared with field galaxies of the same stellar mass and at the same redshift. We conclude that most of the stellar mass in these groups was already in place by z~0.4, with little environment-driven evolution to the present day.Comment: Accepted for publication in MNRAS. 13 pages mn2e style, with 11 figures and 4 table

GMASS ultradeep spectroscopy of galaxies at z ~ 2

“…Applying a total-to-stellar-mass ratio of 100, appropriate for clusters with a velocity dispersion in the range 425-800 km s −1 (Balogh et al 2007), in a similar way to the approach of McCarthy et al (2007) for a structure at z = 1.5, we obtain a total mass of ∼6 × 10 13 M , which is consistent with the mass obtained above for the sphere circumscribing the high-density region. Castellano et al (2007) reported three X-ray sources within the high-density region, one coinciding with the peak of their galaxy density contours and including a late-type galaxy of a peculiar morphology.…”

“…Although this Butcher-Oemler effect has been disputed, the general conclusion still stands (e.g., Ellingson et al 2001;Tanaka et al 2005;Andreon et al 2006;Tran et al 2007;Fassbender et al 2008). Balogh et al (2007) find that, for a given stellar mass and redshift, fewer galaxies in groups show strong [O ii] emission than in field galaxies. The evolution of star formation rate appears to depend on both galaxy mass and galaxy environment (Baldry et al 2006).…”

The zCOSMOS redshift survey: how group environment alters global downsizing trends

“…It could be explained by a different time of assembly of galaxies in haloes of different masses, a nature mechanism that results in a more evolved galaxy population in groups and clusters, at fixed stellar mass, in a given redshift bin (see Gao et al 2005;Balogh et al 2007).…”

“…are primarily determined by the mass of the dark matter halo in which the galaxy resides (Cooray & Sheth 2002), and that, at a given mass, in overdense environments dark matter haloes assemble at higher redshifts than in underdense environments (Gao et al 2005). This framework could provide a simple way of explaining the observed trends in colors with galaxy luminosity, mass and environment, at low (De Propris et al 2004;Blanton & Berlind 2007) and also at high redshifts (Wilman et al 2005a;Balogh et al 2007), without resorting to any specific mechanisms acting in groups. Two large recent redshift surveys, VVDS and DEEP2, have addressed this problem by studying both groups (Gerke et al 2007;Cucciati et al 2009b) and local density field measurements (Cucciati et al 2006;Cooper et al 2006Cooper et al , 2007, although both studies considered both luminosity selected samples, a choice that, as we discuss later, offers only partial insight into the problem.…”

Evidence for a change in the dominant satellite galaxy quenching mechanism atz = 1

“…Comparable work on more common, lower-mass haloes at z > 0.3 -the progenitors of today's massive clusters -is more difficult and hence more limited, but several studies have shown that group galaxies indeed evolve differently from the field, at least for z < 0.8 (e.g. Wilman et al 2005;Balogh et al 2007;Poggianti et al 2008;Rudnick et al 2009;McGee et al 2011;Knobel et al 2013). At z > 0.8, however, little is known about galaxy evolution in group and low-mass cluster haloes.…”