Poggianti, Bianca M. and Aragόn-Salamanca, Alfonso and Zaritsky, Dennis and D- Lucia, Gabriella and Milvang-Jensen, Bo and Desai, Vandana and Jablonka, Pascale and Halliday, Claire and Rudnick, Gregory and Varela, Jesus and Bamford, Steven and Best, Philip and Clowe, Douglas and Noll, Stefan and Saglia, Roberto and Pellό, Roser and Simard, Luc and von-der-Linden, Anja and White, Simon (2009) The Environments of Starburst and Post-Starburst Galaxies at z = 0.4-0.8. Astrophysical Journal, 693 (1). pp. 112-131. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090924-133604695
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Post-starburst (E+A or k+a) spectra, characterized by their exceptionally strong Balmer lines in absorption and the lack of emission lines, belong to galaxies in which the star formation (SF) activity ended abruptly sometime during the past Gyr. We perform a spectral analysis of galaxies in clusters, groups, poor groups, and the field at z = 0.4-0.8 based on the ESO Distant Cluster Survey. We find that the incidence of k+a galaxies at these redshifts depends strongly on environment. K+a's reside preferentially in clusters and, unexpectedly, in a subset of the σ = 200-400 km s^(–1) groups, those that have a low fraction of O II emitters. In these environments, 20%-30% of the star-forming galaxies have had their SF activity recently truncated. In contrast, there are proportionally fewer k+a galaxies in the field, the poor groups, and groups with a high O II fraction. An important result is that the incidence of k+a galaxies correlates with the cluster velocity dispersion: more massive clusters have higher proportions of k+a's. Spectra of dusty starburst candidates, with strong Balmer absorption and emission lines, present a very different environmental dependence from k+a's. They are numerous in all environments at z = 0.4-0.8, but they are especially numerous in all types of groups, favoring the hypothesis of triggering by a merger. We present the morphological type, stellar mass, luminosity, mass-to-light ratio, local galaxy density, and clustercentric distance distributions of galaxies of different spectral types. These properties are consistent with previous suggestions that cluster k+a galaxies are observed in a transition phase, at the moment they are rather massive S0 and Sa galaxies, evolving from star-forming, recently infallen later types to passively evolving cluster early-type galaxies. The correlation between k+a fraction and cluster velocity dispersion supports the hypothesis that k+a galaxies in clusters originate from processes related to the intracluster medium, while several possibilities are discussed for the origin of the puzzling k+a frequency in low-O II groups.
|Additional Information:||© 2009. The American Astronomical Society. Received 2008 July 23, accepted for publication 2008 November 2. Published 2009 February 27. We would like to thank John Moustakas for helpful discussions and for sharing unpublished results, Fabio Barazza for providing his bar classification catalog, and the anonymous referee whose report triggered several improvements in the paper. B.M.P. thanks the Alexander von Humboldt Foundation and the Max Planck Instituut für Extraterrestrische Physik in Garching for a very pleasant and productive stay during which the work presented in this paper was carried out. B.M.P. acknowledges financial support from the National Institute for Astrophysics (INAF) through its PRIN-INAF2006 scheme. The Dark Cosmology Centre is funded by the Danish National Research Foundation.|
|Subject Keywords:||galaxies: clusters: general; galaxies: evolution; galaxies: stellar content|
|Official Citation:||The Environments of Starburst and Post-Starburst Galaxies at z = 0.4-0.8 Bianca M. Poggianti, Alfonso Aragón-Salamanca, Dennis Zaritsky, Gabriella De Lucia, Bo Milvang-Jensen, Vandana Desai, Pascale Jablonka, Claire Halliday, Gregory Rudnick, Jesus Varela, Steven Bamford, Philip Best, Douglas Clowe, Stefan Noll, Roberto Saglia, Roser Pelló, Luc Simard, Anja von der Linden, and Simon White 2009 ApJ 693 112-131 doi: 10.1088/0004-637X/693/1/112|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||25 Sep 2009 18:25|
|Last Modified:||26 Dec 2012 11:25|
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