The relation between star formation, morphology and local density in high redshift clusters and groups

Abstract

We investigate how the [OII] properties and the morphologies of galaxies in clusters and groups at z=0.4-0.8 depend on projected local galaxy density, and compare with the field at similar redshifts and clusters at low-z. In both nearby and distant clusters, higher-density regions contain proportionally fewer star-forming galaxies, and the average [OII] equivalent width of star-forming galaxies is independent of local density. However, in distant clusters the average current star formation rate (SFR) in star-forming galaxies seems to peak at densities ~15-40 galaxies Mpc^{-2}. At odds with low-z results, at high-z the relation between star-forming fraction and local density varies from high- to low-mass clusters. Overall, our results suggest that at high-z the current star formation (SF) activity in star-forming galaxies does not depend strongly on global or local environment, though the possible SFR peak seems at odds with this conclusion. We find that the cluster SFR normalized by cluster mass anticorrelates with mass and correlates with the star-forming fraction. These trends can be understood given a) that the average star-forming galaxy forms about 1 Msun/yr in all clusters; b) that the total number of galaxies scales with cluster mass and c) the dependence of star-forming fraction on cluster mass. We present the morphology-density (MD) relation for our z=0.4-0.8 clusters, and uncover that the decline of the spiral fraction with density is entirely driven by galaxies of types Sc or later. For galaxies of a given Hubble type, we see no evidence that SF properties depend on local environment. In contrast with recent findings at low-z, in our distant clusters the SF-density relation and the MD-relation are equivalent, suggesting that neither of the two is more fundamental than the other.(abr.)

21 pages, 14 figures, accepted for publication in ApJ

References in corpus (6)

• The build-up of the colour-magnitude relation in galaxy clusters since z~0.8
• The Dependence of Galaxy Morphology and Structure on Environment and Stellar Mass
• Galaxy Colour, Morphology, and Environment in the Sloan Digital Sky Survey
• Spectroscopy of clusters in the ESO distant cluster survey (EDisCS).II. Redshifts, velocity dispersions, and substructure for clusters in the last 15 fields
• Mass and Redshift Dependence of Star Formation in Relaxed Galaxy Clusters
• Discovery of a single faint AGN in a large sample of z>5 Lyman break galaxies

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• Serendipitous Discovery of an Overdensity of Lyman-Alpha Emitters at z~4.8 in the Cl1604 Supercluster Field
• Evidence for Morphology and Luminosity Transformation of Galaxies at High Redshifts
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