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The 24 Micron Source Counts in Deep Spitzer Space Telescope Surveys

Papovich, C. and Dole, H. and Egami, E. and Le Floc'h, E. and Pérez‐González, P. G. and Alonso‐Herrero, A. and Bai, L. and Beichman, C. A. and Blaylock, M. and Engelbracht, C. W. and Gordon, K. D. and Hines, D. C. and Misselt, K. A. and Morrison, J. E. and Mould, J. and Muzerolle, J. and Neugebauer, G. and Richards, P. L. and Rieke, G. H. and Rieke, M. J. and Rigby, J. R. and Su, K. Y. L. and Young, E. T. (2004) The 24 Micron Source Counts in Deep Spitzer Space Telescope Surveys. Astrophysical Journal Supplement Series, 154 (1). pp. 70-74. ISSN 0067-0049. doi:10.1086/422880.

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Galaxy source counts in the infrared provide strong constraints on the evolution of the bolometric energy output from distant galaxy populations. We present the results from deep 24 μm imaging from Spitzer surveys, which include ≈5 × 10^4 sources to an 80% completeness of ≃ 60 μJy. The 24 μm counts rapidly rise at near-Euclidean rates down to 5 mJy, increase with a super-Euclidean rate between 0.4 and 4 mJy, and converge below ~0.3 mJy. The 24 μm counts exceed expectations from nonevolving models by a factor of ≳10 at S_ν ~ 0.1 mJy. The peak in the differential number counts corresponds to a population of faint sources that is not expected from predictions based on 15 μm counts from the Infrared Space Observatory. We argue that this implies the existence of a previously undetected population of infrared-luminous galaxies at z ~ 1-3. Integrating the counts to 60 μJy, we derive a lower limit on the 24 μm background intensity of 1.9 ± 0.6 nW m^(-2) sr^(-1) of which the majority (~60%) stems from sources fainter than 0.4 mJy. Extrapolating to fainter flux densities, sources below 60 μJy contribute 0.8^(+0.9)_(-0.4) nW m^(-2) sr^(-1) to the background, which provides an estimate of the total 24 μm background of 2.7^(+1.1)_(-0.7) nW m^(-2) sr^(-1).

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Papovich, C.0000-0001-7503-8482
Beichman, C. A.0000-0002-5627-5471
Hines, D. C.0000-0003-4653-6161
Mould, J.0000-0003-3820-1740
Muzerolle, J.0000-0002-5943-1222
Rieke, G. H.0000-0003-2303-6519
Rieke, M. J.0000-0002-7893-6170
Rigby, J. R.0000-0002-7627-6551
Su, K. Y. L.0000-0002-3532-5580
Additional Information:© 2004 American Astronomical Society. Received 2004 March 25. Accepted 2004 May 17. We acknowledge our colleagues for stimulating conversations, the Spitzer Science Center staff for efficient data processing, Thomas Soifer and the IRS team for executing the Boötes-field observations, Daniel Eisenstein for cosmology discussions, Jim Cadien for his assistance with the data reduction, and the entire Spitzer team for their concerted effort. We also thank the referee, Matthew Malkan, for a thorough and insightful report. Support for this work was provided by NASA through contract 960785 issued by JPL/Caltech.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: high-redshift; galaxies: photometry; infrared: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20170808-142319074
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Official Citation:C. Papovich et al 2004 ApJS 154 70
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79953
Deposited By: Ruth Sustaita
Deposited On:09 Aug 2017 16:23
Last Modified:15 Nov 2021 17:51

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