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Keck Deep Fields. II. The Ultraviolet Galaxy Luminosity Function at z ~ 4, 3, and 2

Sawicki, Marcin and Thompson, David (2006) Keck Deep Fields. II. The Ultraviolet Galaxy Luminosity Function at z ~ 4, 3, and 2. Astrophysical Journal, 642 (2). pp. 653-672. ISSN 0004-637X. doi:10.1086/500999.

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We use very deep U_nGRI multifield imaging obtained at the Keck telescope to study the evolution of the rest-frame 1700 Å galaxy luminosity function as the universe doubles its age from z ~ 4 to ~2. We use exactly the same filters and color-color selection as those used by the Steidel team but probe significantly fainter limits, well below L^*. The depth of our imaging allows us to constrain the faint end of the luminosity function, reaching M_(1700) ~ -18.5 at z ~ 3 (equivalent to ~1 M_⊙ yr^(-1)), accounting for both N^(1/2) uncertainty in the number of galaxies and cosmic variance. We carefully examine many potential sources of systematic bias in our LF measurements before drawing the following conclusions. We find that the luminosity function of Lyman break galaxies evolves with time and that this evolution is differential with luminosity. The result is best constrained between the epochs at z ~ 4 and ~3, where we find that the number density of sub-L^* galaxies increases with time by at least a factor of 2.3 (11 σ statistical confidence); while the faint end of the LF evolves, the bright end appears to remain virtually unchanged, indicating that there may be differential, luminosity-dependent evolution (98.5% statistical probability). Potential systematic biases restrict our ability to draw strong conclusions about continued evolution of the luminosity function to lower redshifts, z ~ 2.2 and ~1.7, but, nevertheless, it appears certain that the number density of z ~ 2.2 galaxies at all luminosities we studied, -22 > M_(1700) > -18, is at least as high as that of their counterparts at z ~ 3. While it is not yet clear what mechanism underlies the observed evolution, the fact that this evolution is differential with luminosity opens up new avenues of improving our understanding of how galaxies form and evolve at high redshift.

Item Type:Article
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Sawicki, Marcin0000-0002-7712-7857
Additional Information:© 2006 The American Astronomical Society. Received 2005 April 25; accepted 2005 December 14. We thank the Palomar time allocation committee for a generous time allocation that made this project possible and the staff of the W. M. Keck Observatory for their help in obtaining these data. We are grateful to Chuck Steidel for his encouragement and support of this project and Jerzy Sawicki for many useful comments. We also thank Masami Ouchi and Armin Gabasch for providing their LF data points in tabular format and Naveen Reddy and Ikuru Iwata for useful discussions. Finally, we wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community; we are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies : evolution; galaxies : formation; galaxies : high-redshift; galaxies : starburst
Issue or Number:2
Record Number:CaltechAUTHORS:20100421-152316924
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Official Citation: Marcin Sawicki and David Thompson 2006 ApJ 642 653 doi: 10.1086/500999
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18045
Deposited By: Tony Diaz
Deposited On:11 May 2010 20:37
Last Modified:08 Nov 2021 23:41

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