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Published January 2006 | Published + Submitted
Journal Article Open

Spitzer 70 and 160 μm Observations of the Extragalactic First Look Survey


We present 70 and 160 μm observations from the Spitzer extragalactic First Look Survey (xFLS). The data reduction techniques and the methods for producing co-added mosaics and source catalogs are discussed. Currently, 26% of the 70 μm sample and 49% of the 160 μm–selected sources have redshifts. The majority of sources with redshifts are star-forming galaxies at z < 0.5, while about 5% have infrared colors consistent with active galactic nuclei. The observed infrared colors agree with the spectral energy distributions (SEDs) of local galaxies previously determined from IRAS and Infrared Space Observatory data. The average 160 μm/70 μm color temperature for the dust is T_d ≃ 30 ± 5 K, and the average 70 μm/24 μm spectral index is α ≃ 2.4 ± 0.4. The observed infrared-to-radio correlation varies with redshift as expected out to z ~ 1 based on the SEDs of local galaxies. The xFLS number counts at 70 and 160 μm are consistent within uncertainties with the models of galaxy evolution, but there are indications that the current models may require slight modifications. Deeper 70 μm observations are needed to constrain the models, and redshifts for the faint sources are required to measure the evolution of the infrared luminosity function.

Additional Information

© 2006 The American Astronomical Society. Received 2005 August 1; accepted 2005 September 21. We thank all of our colleagues associated with the Spitzer mission who have made these observations possible. 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.

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Published - Frayer_2006_AJ_131_250.pdf

Submitted - 0509649.pdf


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