Peter, Annika H. G. and Shapley, Alice E. and Law, David R. and Steidel, Charles C. and Erb, Dawn K. and Reddy, Naveen A. and Pettini, Max (2007) Morphologies of Galaxies in and around a Protocluster at z = 2.300. Astrophysical Journal, 668 (1). pp. 23-44. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:PETapj07
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We present results from the first robust investigation of galaxy morphology as a function of environment at z > 1.5. Our study is motivated by the fact that star-forming galaxies contained within a protocluster at z = 2.3 in the HS 1700+64 field have significantly older ages and larger stellar masses on average than those at similar redshifts but more typical environmental densities. In the analysis of HST ACS images, we apply nonparametric statistics to characterize the rest-frame UV morphologies of a sample of 85 UV-selected star-forming galaxies at z = 1.7-2.9, 22 of which are contained in the protocluster. The remaining 63 control sample galaxies are not in the protocluster but have a similar mean redshift of zbar ~ 2.3. We find no environmental dependence for the distributions of morphological properties. Combining the measured morphologies with the results of population synthesis modeling, we find only weak correlations, if any, between morphological and stellar population properties such as stellar mass, age, extinction, and star formation rate. Given the incomplete census of the protocluster galaxy population, and the lack of correlation between rest-frame UV morphology and star formation history at z ~ 2 within our sample, the absence of environmental trends in the distribution of morphological properties is not surprising. In addition, using a larger sample of photometric candidates, we compare morphological distributions for 282 UV-selected and 43 near-IR-selected galaxies. While the difference in the degree of nebulosity between the two samples appears to be a by-product of the fainter average rest-frame UV surface brightness of the near-IR-selected galaxies, we find that, among the lowest surface brightness galaxies, the near-IR-selected objects have significantly smaller angular sizes.
|Additional Information:||© 2007. The American Astronomical Society. Received 2007 February 27; accepted 2007 June 16. Print publication: Issue 1 (2007 October 10). Based on observations made with the NASA ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program HST-GO-10581.07-A. Support for program HST-GO-10581.07-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. A.E.S. acknowledges support from the David and Lucile Packard Foundation. C.C.S. and D.R.L. have been supported by grants AST 06-06912 from the US National Science Foundation and HST-AR-10311 from NASA through the Space Telescope Science Institute. We thank Jennifer Lotz for providing us with her morphological analysis of the GOODS-N field, Mauro Giavalisco for useful discussions, and an anonymous referee, whose comments improved the paper.|
|Subject Keywords:||cosmology: observations; galaxies: clusters: general; galaxies: high-redshift; galaxies: structure|
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|Deposited On:||14 Jan 2009 22:19|
|Last Modified:||26 Dec 2012 10:43|
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