Poggianti, Bianca M. and Desai, Vandana and Finn, Rose and Bamford, Steven and De Lucia, Gabriella and Varela, Jesus and Aragón-Salamanca, Alfonso and Halliday, Claire and Noll, Stefan and Saglia, Roberto and Zaritsky, Dennis and Best, Philip and Clowe, Douglas and Milvang-Jensen, Bo and Jablonka, Pascale and Pelló, Roser and Rudnick, Gregory and Simard, Luc and von der Linden, Anja and White, Simon (2008) The relation between star formation, morphology, and local density in high-redshift clusters and groups. Astrophysical Journal, 684 (2). pp. 888-904. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090526-140442640
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We investigate how the [O II] 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 [O II] 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 (1) that the average star-forming galaxy forms about 1⊙M yr^−1 (uncorrected for dust) in all clusters; (2) that the total number of galaxies scales with cluster mass; and (3) 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 type 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.
|Additional Information:||© 2008 The American Astronomical Society. Received 2008 March 20; accepted 2008 May 7. We would like to thank the referee, Arjen van der Wel, for the constructive and careful report that helped us improving the paper. B. M. P. thanks the Alexander von Humboldt Foundation and the Max Planck Instituut fur Extraterrestrische Physik in Garching for a very pleasant and productive stay during which the work presented in this paper was carried out. The Dark Cosmology Centre is funded by the Danish National Research Foundation. B. M. P. acknowledges financial support from the FIRB scheme of the Italian Ministry of Education, University and Research (RBAU018Y7E) and from the INAFY National Institute for Astrophysics through its PRIN-INAF2006 scheme. Facilities: VLT(FORS2), HST(ACS). Based on observations collected at the European Sputhern Observatory, Chile, as part of large program 166.A-0162 (the ESO Distant Cluster Survey) and with the NASA/ESA Hubble Space Telescope with proposal 9476. Print publication: Issue 2 (2008 September 10).|
|Subject Keywords:||galaxies: clusters: general; galaxies: evolution; galaxies: stellar content|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||27 May 2009 18:18|
|Last Modified:||26 Dec 2012 11:01|
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