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Counts and colours of faint galaxies in the U and R bands

Hogg, David W. and Pahre, Michael A. and McCarthy, James K. and Cohen, Judith G. and Blandford, Roger and Smail, Ian and Soifer, B. T. (1997) Counts and colours of faint galaxies in the U and R bands. Monthly Notices of the Royal Astronomical Society, 288 (2). pp. 404-410. ISSN 0035-8711. doi:10.1093/mnras/288.2.404.

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Ground-based counts and colours of faint galaxies in the U and R bands in one field at high Galactic latitude are presented. Integrated over flux, a total of 1.2 × 10^5 source deg^(−2) are found to U = 25.5 mag and 6.3 × 10^5 source deg^(−2) to R = 27 mag, with d log N/dm ∼ 0.5 in the U band and d log N/dm ∼ 0.3 in the R band. Consistent with these number-magnitude curves, sources become bluer with increasing magnitude to median U— R= 0.6 mag at 24<U<25 mag and U — R = 1.2 mag at 25 < R < 26 mag. Because the Lyman break redshifts into the U band at z ≈ 3, at least 1.2 × 10^5 source deg^(−2) must be at redshifts z < 3. Measurable U-band fluxes of 73 per cent of the 6.3 × 10^5 source deg^(−2) suggest that the majority of these also lie at z < 3. These results require an enormous space density of objects in any cosmological model.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hogg, David W.0000-0003-2866-9403
Cohen, Judith G.0000-0002-8039-4673
Blandford, Roger0000-0002-1854-5506
Smail, Ian0000-0003-3037-257X
Additional Information:© 1997 RAS. Accepted 1997 February 15. Received 1997 February 5; in original form 1996 April 15. We are grateful to the W. M. Keck Foundation for the vision to fund the construction of the W. M. Keck Observatory. We benefited from helpful conversations with Kurt Adelberger, John Gizis, Tomislav Kundic, Gerry Neugebauer, Sterl Phinney and Chuck Steidel, and from comments from an anonymous referee. We are grateful for financial support from NSF grant AST 92-23370 (DWH, RB), NSF grant AST-91-57412 and the Bressler Foundation (MAP), support through a PPARC Advanced Fellowship (IS), and grants from NSF and NASA (BTS). The calibrated images used for this investigation will be made available to the public; contact the authors for more information. This work is based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California; and at the Palomar Observatory, which is owned and operated by the California Institute of Technology.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
NSFAST 92-23370
NSFAST 91-57412
Bressler FoundationUNSPECIFIED
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Subject Keywords:galaxies: fundamental parameters, galaxies: photometry, cosmology: observations, ultraviolet: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20190523-125439368
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Official Citation:David W. Hogg, Michael A. Pahre, James K. McCarthy, Judith G. Cohen, Roger Blandford, Ian Smail, B. T. Soifer, Counts and colours of faint galaxies in the U and R bands, Monthly Notices of the Royal Astronomical Society, Volume 288, Issue 2, 21 June 1997, Pages 404–410,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95755
Deposited By: George Porter
Deposited On:23 May 2019 22:11
Last Modified:16 Nov 2021 17:15

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