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Published February 10, 2010 | Published
Journal Article Open

Comparing the Relation Between Star Formation and Galaxy Mass in Different Environments

Abstract

Analyzing 24 μm MIPS/Spitzer data and the [O II]3727 line of a sample of galaxies at 0.4 ≤ z ≤ 0.8 from the ESO Distant Cluster Survey, we investigate the ongoing star formation rate (SFR) and the specific star formation rate (SSFR) as a function of stellar mass in galaxy clusters and groups, and compare these with results from field studies. As for the field, we find a decline in SFR with time, indicating that star formation (SF) was more active in the past, and a decline in SSFR as galaxy stellar mass increases, showing that the current SF contributes more to the fractional growth of low-mass galaxies than high-mass galaxies. However, we find a lower median SFR (by a factor of ~1.5) in cluster star-forming galaxies than in the field. The difference is highly significant when all Spitzer and emission-line galaxies are considered, regardless of color. It remains significant at z > 0.6 after removing red emission-line galaxies, to avoid possible active galactic nucleus contamination. While there is overlap between the cluster and field SFR-mass relations, we find a population of cluster galaxies (10%-25%) with reduced SFR for their mass. These are likely to be in transition from star forming to passive. Separately comparing clusters and groups at z > 0.6, only cluster trends are significantly different from the field, and the average cluster SFR at a given mass is ~two times lower than the field. We conclude that the average SFR in star-forming galaxies varies with galaxy environment at a fixed galaxy mass.

Additional Information

© 2010 The American Astronomical Society. Received 2009 October 20; accepted 2009 December 4; published 2010 January 19. We thank the anonymous referee for his/her useful remarks. We thank Kai Noeske and the AEGIS collaboration for providing us their data and support.We acknowledge financial support from ASI contract I/016/07/0.

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August 19, 2023
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