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The Evolutionary History of Lyman Break Galaxies Between Redshift 4 and 6: Observing Successive Generations of Massive Galaxies in Formation

Stark, Daniel P. and Ellis, Richard S. and Bunker, Andrew and Bundy, Kevin and Targett, Tom and Benson, Andrew and Lacy, Mark (2009) The Evolutionary History of Lyman Break Galaxies Between Redshift 4 and 6: Observing Successive Generations of Massive Galaxies in Formation. Astrophysical Journal, 697 (2). pp. 1493-1511. ISSN 0004-637X. doi:10.1088/0004-637X/697/2/1493.

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We present new measurements of the evolution in the Lyman break galaxy (LBG) population between z ≃ 4 and z ≃ 6. By utilizing the extensive multiwavelength data sets available in the GOODS fields, we identify 2443 B, 506 V, and 137 i'-band dropout galaxies likely to be at z ≈ 4, 5, and 6. For the subset of dropouts for which reliable Spitzer IRAC photometry is feasible (roughly 35% of the sample), we estimate luminosity-weighted ages and stellar masses. With the goal of understanding the duration of typical star formation episodes in galaxies at z ≳ 4, we examine the distribution of stellar masses and ages as a function of cosmic time. We find that at a fixed rest-UV luminosity, the average stellar masses and ages of galaxies do not increase significantly between z ≃ 6 and 4. In order to maintain this near equilibrium in the average properties of high-redshift LBGs, we argue that there must be a steady flux of young, newly luminous objects at each successive redshift. When considered along with the short duty cycles inferred from clustering measurements, these results may suggest that galaxies are undergoing star formation episodes lasting only several hundred million years. In contrast to the unchanging relationship between the average stellar mass and rest-UV luminosity, we find that the number density of massive galaxies increases considerably with time over 4 ≾ z ≾ 6. Given this rapid increase of UV luminous massive galaxies, we explore the possibility that a significant fraction of massive (10^(11) M⊙) z ≃ 2-3 distant red galaxies (DRGs) were in part assembled in an LBG phase at earlier times. Integrating the growth in the stellar mass function of actively forming LBGs over 4 ≾ z ≾ 6 down to z ≃ 2, we find that z ≳ 3 LBGs could have contributed significantly to the quiescent DRG population, indicating that the intense star-forming systems probed by submillimeter observations are not the only route toward the assembly of DRGs at z ≃ 2.

Item Type:Article
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URLURL TypeDescription
Ellis, Richard S.0000-0001-7782-7071
Bundy, Kevin0000-0001-9742-3138
Benson, Andrew0000-0001-5501-6008
Lacy, Mark0000-0002-3032-1783
Additional Information:© 2009 The American Astronomical Society. Received 2008 October 13; accepted 2009 March 10; published 2009 May 13. We thank the referee for a very useful report and acknowledge helpful conversations with Tommaso Treu, Niv Drory, and Masami Ouchi. D.P.S. thanks the Department of Astrophysics at the University of Oxford for its hospitality while much of this work was being conducted and acknowledges financial support from the STFC. R.S.E. acknowledges financial support from the Royal Society. This paper is based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive 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. The HST/ACS observations are associated with proposals #9425 & 9583 (the GOODS public imaging survey).
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: starburst; surveys; ultraviolet: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20090908-094544877
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Official Citation:The Evolutionary History of Lyman Break Galaxies Between Redshift 4 and 6: Observing Successive Generations of Massive Galaxies in Formation Daniel P. Stark, Richard S. Ellis, Andrew Bunker, Kevin Bundy, Tom Targett, Andrew Benson, and Mark Lacy 2009 ApJ 697 1493-1511 doi: 10.1088/0004-637X/697/2/1493.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15668
Deposited By: Tony Diaz
Deposited On:15 Sep 2009 16:44
Last Modified:08 Nov 2021 23:21

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