Confusion limit resulting from galaxies: using the Infrared Array Camera on board SIRTF |
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Authors: | Petri Vä isä nen,Eric V. Tollestrup,Giovanni G. Fazio |
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Affiliation: | 1Observatory, PO Box 14, 00014 University of Helsinki, Finland;2Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA |
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Abstract: | Recent ISO data have allowed, for the first time, observationally based estimates for source confusion in mid-infrared surveys. We use the extragalactic source counts from ISOCAM in conjunction with K -band counts to predict the confusion resulting from galaxies in deep mid-infrared observations. We specifically concentrate on the near-future Space Infrared Telescope Facility ( SIRTF ) mission, and calculate expected confusion for the Infrared Array Camera (IRAC) on board SIRTF . A defining scientific goal of the IRAC instrument will be the study of high-redshift galaxies using a deep, confusion-limited wide-field survey at 3–10 μm . A deep survey can reach 3-μJy sources with reasonable confidence in the shorter wavelength IRAC bands. Truly confusion-limited images with the 8 μm will be difficult to obtain because of practical time constraints, unless infrared galaxies exhibit very strong evolution beyond the deepest current observations. We find L * galaxies to be detectable to z =3–3.5 at 8 μm, which is slightly more pessimistic than found in 1999 by Simpson & Eisenhardt. |
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Keywords: | methods: observational techniques: photometric galaxies: evolution galaxies: photometry cosmology: observations infrared: galaxies |
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