Overzier, Roderik A. and Bouwens, R. J. and Cross, N. J. G. and Venemans, B. P. and Miley, G. K. and Zirm, A. W. and Benítez, N. and Blakeslee, J. P. and Coe, D. and Demarco, R. and Ford, H. C. and Homeier, N. L. and Illingworth, G. D. and Kurk, J. D. and Martel, A. R. and Mei, S. and Oliveira, I. and Röttgering, H. J. A. and Tsvetanov, Z. I. and Zheng, W. (2008) Lyman break galaxies, Lyα emitters, and a radio galaxy in a protocluster at z = 4.1. Astrophysical Journal, 673 (1). pp. 143-162. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090429-085303864
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We present deep HST ACS observations in g_(475)r_(625)i_(775)z_(850) toward the z = 4.1 radio galaxy TN J1338–1942 and its overdensity of >30 spectroscopically confirmed Lyα emitters (LAEs). We select 66 g_(475) band dropouts to z_(850),(5σ) = 27, 6 of which are also LAEs. Although our color-color selection results in a relatively broad redshift range centered on z = 4.1, the field of TN J1338–1942 is richer than the average field at the > 5 σ significance, based on a comparison with GOODS. The angular distribution is filamentary with about half of the objects clustered near the radio galaxy, and a small, excess signal (2 σ) in the projected pair counts at separations of θ < 10" is interpreted as being due to physical pairs. The LAEs are young (a few times 10^7 yr), small (<r_(hl)> = 0.13") galaxies, and we derive a mean stellar mass of ~10^8-10^9 M⊙ based on a stacked Ks band image. We determine star formation rates, sizes, morphologies, and color-magnitude relations of the g_(475)-dropouts and find no evidence for a difference between galaxies near TN J1338–1942 and in the field. We conclude that environmental trends as observed in clusters at much lower redshift are either not yet present or washed out by the relatively broad selection in redshift. The large galaxy overdensity, its corresponding mass overdensity, and the subclustering at the approximate redshift of TN J1338–1942 suggest the assemblage of a >10^14 M⊙ structure, confirming that it is possible to find and study cluster progenitors in the linear regime at z ≳ 4.
|Additional Information:||© 2008 The American Astronomical Society. Received 2006 January 10; accepted 2007 October 7. We thank Masami Ouchi for invaluable discussions and reading through the manuscript. We would also like to thank Ryan Quadri and Huib Intema for their contributions and the anonymous referee for his/her suggestions. ACS was developed under NASA contract NAS 5-32865, and this research has been supported by NASA grant NAG5-7697 and by an equipment grant from Sun Microsystems, Inc. The Space Telescope Science Institute is operated by AURA, Inc., under NASA contract NAS 5-26555. We are grateful to K. Anderson, J. McCann, S. Busching, A. Framarini, S. Barkhouser, and T. Allen for their invaluable contributions to the ACS project at JHU. J. K. was supported by DFG grant SFB-439.|
|Subject Keywords:||cosmology: observations; early universe; galaxies: clusters: general; galaxies: high-redshift; galaxies: individual (TN J1338-1942); galaxies: starburst; large-scale structure of universe|
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|Deposited By:||Tony Diaz|
|Deposited On:||29 Apr 2009 17:31|
|Last Modified:||26 Dec 2012 10:59|
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