The Nature of Star Formation at 24 microns in the Group Environment at 0.3 < z < 0.55

Abstract

Galaxy star formation rates (SFRs) are sensitive to the local environment; for example, the high-density regions at the cores of dense clusters are known to suppress star formation. It has been suggested that galaxy transformation occurs largely in groups, which are the intermediate step in density between field and cluster environments. In this paper, we use deep MIPS 24 micron observations of intermediate-redshift (0.3 < z < 0.55) group and field galaxies from the Group Environment and Evolution Collaboration (GEEC) subset of the Second Canadian Network for Observational Cosmology (CNOC2) survey to probe the moderate-density environment of groups, wherein the majority of galaxies are found. The completeness limit of our study is log(L_TIR (L_sun)) > 10.5, corresponding to SFR > 2.7 M_sun/yr. We find that the group and field galaxies have different distributions of morphologies and mass. However, individual group galaxies have star-forming properties comparable to those of field galaxies of similar mass and morphology; that is, the group environment does not appear to modify the properties of these galaxies directly. There is a relatively large number of massive early-type group spirals, along with E/S0 galaxies, that are forming stars above our detection limit. These galaxies account for the nearly comparable level of star-forming activity in groups as compared with the field, despite the differences in mass and morphology distributions between the two environments. The distribution of specific SFRs (SFR/M_*) is shifted to lower values in the groups, reflecting the fact that groups contain a higher proportion of massive and less active galaxies. Considering the distributions of morphology, mass, and SFR, the group members appear to lie between field and cluster galaxies in overall properties.

Accepted to ApJ. 44 pages, 13 figures

References in corpus (23)

• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• UV Star Formation Rates in the Local Universe
• Ram pressure stripping the hot gaseous halos of galaxies in groups and clusters
• Strangulation in Galaxy Groups
• The DEEP2 Galaxy Redshift Survey: Evolution of the Color-Density Relation at 0.4 < z < 1.35
• The Dawn of the Red: Star formation histories of group galaxies over the past 5 billion years
• The DEEP2 galaxy redshift survey: the evolution of the blue fraction in groups and the field
• The Infrared Properties of Hickson Compact Groups
• The UV colours of high-redshift early-type galaxies: evidence for recent star formation and stellar mass assembly over the last 8 billion years
• IR observations of MS 1054-03: Star Formation and its Evolution in Rich Galaxy Clusters
• Strong dusty bursts of star formation in galaxies falling into the cluster RXJ0152.7-1357
• Exploring the evolutionary paths of the most massive galaxies since z~2
• The IR Luminosity Functions of Rich Clusters
• Dust-Obscured Star-Formation in Intermediate Redshift Galaxy Clusters
• The UV luminosity function and star formation rate of the Coma cluster
• Unveiling the Important Role of Groups in the Evolution of Massive Galaxies: Insights from an Infrared Passive Sequence at Intermediate Redshift
• The stellar mass content of distant galaxy groups
• The Color Bimodality in Galaxy Clusters since z = 0.9
• Evolution in the Disks and Bulges of Group Galaxies since z=0.4
• The Environment on few Mpc scales of Infrared Luminous Galaxies at Redshifts z~1
• Limits on the AGN activities in X-ray underluminous galaxy groups
• Low Star Formation Rates for z=1 Early-Type Galaxies in the Very Deep GOODS-MIPS Imaging: Implications for their Optical/Near-Infrared Spectral Energy Distributions

Cited by in corpus (4)

• On the evolution and environmental dependence of the star formation rate versus stellar mass relation since z~2
• Substructure in the Most Massive GEEC Groups: Field-like Populations in Dynamically Active Groups
• Do group dynamics play a role in the evolution of member galaxies?
• Detection of Outflowing and Extraplanar Gas in Disks in an Assembling Galaxy Cluster at z=0.37