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Counting individual galaxies from deep 24-μm Spitzer surveys

Rodighiero, G. and Lari, C. and Pozzi, F. and Gruppioni, C. and Fadda, D. and Franceschini, A. and Lonsdale, C. and Surace, J. and Shupe, D. and Fang, F. (2006) Counting individual galaxies from deep 24-μm Spitzer surveys. Monthly Notices of the Royal Astronomical Society, 371 (4). pp. 1891-1897. ISSN 0035-8711. doi:10.1111/j.1365-2966.2006.10844.x.

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We address the question of how to deal with confusion-limited surveys in the mid-infrared (MIR) domain by using information from shorter-wavelength observations over the same sky regions. Such information, once applied to apparently extended MIR sources, which are indeed ‘blends’ of two or more different sources, allow us to disentangle the single counterparts and to split the measured flux density into different components. We present the application of this method to the 24-μm Spitzer archival data in the Great Observatories Origins Deep Survey ELAIS-N1 (GOODS EN1) test field, where apparently extended, ‘blended’ sources constitute about 20 per cent of a reliable sample of 983 sources detected above the 5σ threshold down to 40 μJy. As a shorter-wavelength data set, we have considered the public Infrared Array Camera (IRAC) images and catalogues of the same field. We show that the 24-μm sample is almost unbiased down to ~40 μJy and the careful application of the deblending procedure does not require any statistical completeness correction (at least at the flux level considered). This is probed by direct comparison of our results with results in the literature that analysed the same data set through extensive Monte Carlo simulations. The extrapolation of the source counts down to fainter fluxes suggests that our 24-μm sample is able to resolve ~62 per cent of the cosmic background down to a flux level of 38 μJy.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rodighiero, G.0000-0002-9415-2296
Gruppioni, C.0000-0002-5836-4056
Fadda, D.0000-0002-3698-7076
Lonsdale, C.0000-0003-0898-406X
Surace, J.0000-0001-7291-0087
Shupe, D.0000-0003-4401-0430
Additional Information:© 2006 The Authors. Journal compilation © 2006 RAS. Accepted 2006 July 17. Received 2006 July 17; in original form 2005 July 11. Article first published online: 31 Aug. 2006. We thank an anonymous referee for careful comments that improved the quality of the paper. This work is based on observations made with the Spitzer Space Telescope, which is operated 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:methods: data analysis; catalogues; galaxies: photometry; infrared: galaxies; infrared: general
Issue or Number:4
Record Number:CaltechAUTHORS:20110719-112148848
Persistent URL:
Official Citation:Rodighiero, G., Lari, C., Pozzi, F., Gruppioni, C., Fadda, D., Franceschini, A., Lonsdale, C., Surace, J., Shupe, D. and Fang, F. (2006), Counting individual galaxies from deep 24-μm Spitzer surveys. Monthly Notices of the Royal Astronomical Society, 371: 1891–1897. doi: 10.1111/j.1365-2966.2006.10844.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24461
Deposited On:19 Jul 2011 20:17
Last Modified:09 Nov 2021 16:23

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