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GOODS Spitzer IRAC observations of high-z galaxies – Implications for reionization

Yan, Haojing and Dickinson, Mark and Stern, Daniel and Eisenhardt, Peter R. M. and Chary, Ranga-Ram and Giavalisco, Mauro and Ferguson, Henry C. and Casertano, Stefano and Conselice, Christopher J. and Papovich, Casey and Reach, William T. and Grogin, Norman and Moustakas, Leonidas A. and Ouchi, Masami (2006) GOODS Spitzer IRAC observations of high-z galaxies – Implications for reionization. New Astronomy Reviews, 50 (1-3). pp. 127-133. ISSN 1387-6473.

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A significant number of Lyman-break galaxies (LBGs) at z ≈ 6 and 5 in the Hubble Ultradeep Field (HUDF) have been detected by the Great Observatories Origins Deep Survey (GOODS) observations with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We find that the SEDs for many of these IRAC-detected high-z galaxies are best fitted by models of stellar populations with masses of a few × 10^(10) M_⊙, and with ages of a few hundred million years. This implies that at least some of the galaxies that are responsible for finishing reionization at z ≈ 6 started forming their stars at z > 7 and earlier. The lower limits to the space density for high-z galaxies in this mass range are consistent with predictions from recent hydrodynamic simulations of structure formation in a ΛCDM universe. All objects in our samples are consistent with having solar metallicity, suggesting that the sources that contributed ionizing photons at z ≈ 6 might not be comprised of “first stars”. Some of these galaxies have rest-frame UV colors that are bluer than those predicted by the stellar population models to which we compare them, and can be explained by the presence of very massive stars (>100 M_⊙). This suggests that very massive stars might play an important role in producing ionizing photons in the early stage of the universe. The analysis of z ≈ 6 LBGs has been extended to the entire GOODS fields, HDF-N and CDF-S, and we report the preliminary results.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Dickinson, Mark0000-0001-5414-5131
Stern, Daniel0000-0003-2686-9241
Chary, Ranga-Ram0000-0001-7583-0621
Giavalisco, Mauro0000-0002-7831-8751
Ferguson, Henry C.0000-0001-7113-2738
Conselice, Christopher J.0000-0003-1949-7638
Papovich, Casey0000-0001-7503-8482
Reach, William T.0000-0001-8362-4094
Moustakas, Leonidas A.0000-0003-3030-2360
Ouchi, Masami0000-0002-1049-6658
Additional Information:© 2005 Elsevier B.V. Available online 6 January 2006. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through Contract Number 1224666 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:Cosmology: observations; Galaxies: evolution; Galaxies: luminosity function; Mass function; Infrared: galaxies
Issue or Number:1-3
Record Number:CaltechAUTHORS:20110225-150419807
Persistent URL:
Official Citation:Haojing Yan, Mark Dickinson, Daniel Stern, Peter R.M. Eisenhardt, Ranga-Ram Chary, Mauro Giavalisco, Henry C. Ferguson, Stefano Casertano, Christopher J. Conselice, Casey Papovich, William T. Reach, Norman Grogin, Leonidas A. Moustakas, Masami Ouchi, GOODS spitzer IRAC observations of high-z galaxies - Implications for reionization, New Astronomy Reviews, Volume 50, Issues 1-3, First Light and Reionization: Theoretical Study and Experimental Detection of First Luminous Sources in the Universe, March 2006, Pages 127-133, ISSN 1387-6473, DOI: 10.1016/j.newar.2005.11.026. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22529
Deposited By: Benjamin Perez
Deposited On:25 Feb 2011 23:28
Last Modified:09 Mar 2020 13:19

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