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Confusion limit due to galaxies: using SIRTF's Infrared Array Camera

P. Vaisanen·E. V. Tollestrup·G. G. Fazio
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Abstract

Recent ISO-data has 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 due to galaxies in deep mid-IR observations. We specifically concentrate on the near-future Space Infrared Telescope Facility (SIRTF) mission, and calculate expected confusion for the Infrared Array Camera (IRAC) onboard 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 microns. A deep survey can reach 3 $μ$Jy sources with reasonable confidence in the shorter wavelength IRAC bands. Truly confusion limited images at 8 microns will be difficult to obtain due to practical time constraints, unless infrared galaxies exhibit very strong evolution beyond the deepest current observations. We find L^star galaxies to be detectable to z=3-3.5 at 8 microns, which is slightly more pessimistic than found by Simpson & Eisenhardt (1999).

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P. Vaisanen, E. V. Tollestrup, G. G. Fazio. 2001-06-06. Confusion limit due to galaxies: using SIRTF's Infrared Array Camera. https://doi.org/10.1046/j.1365-8711.2001.04566.x

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