2006ApJ...644..769D

We investigate the redshift dependence of the contribution to the extragalactic far-infrared/submillimeter background from galaxies detected by the Spitzer Space Telescope at 8 and 24 µm. Using seven-band optical to mid-infrared photometry, we estimate photometric redshifts for the Spitzer sources that appear to be mostly L_*galaxies at a median redshift of z=1.0. These sources, extracted from deep 8 and 24 µm mosaics of the CUDSS 14 hour field with 5 σ limits of 5.8 and 70 µJy, respectively, exhibit significant 850 and 450 µm emission as observed by SCUBA. At 850 µm, after removing ≥4 σ sources and those securely identified in our companion cross-matching paper, we measure stacked flux at the significance level of 4.4 and 2.9 σ from the full 8 and 24 µm galaxy catalog, respectively. At 450 µm, flux is detected from all 8 µm galaxies at the level of 3.5 σ, while there is no significant emission from the 24 µm galaxies. We find that the 850 µm flux is emitted almost exclusively at z≳1.3 from the Spitzer sources with 0.44 mJy (4.7 σ) per 8 µm source, and 0.51 mJy (2.8 σ) per 24 µm source. This corresponds to a contribution of (16±3)% toward the 850 µm extragalactic background from the 8 µm sources, and (5.0±1.8)% from the 24 µm sources. At 450 µm, only the 8 µm sources within the redshift interval 1<z<2 exhibit significant emission with an average flux per source of 3.35 mJy (3.0 σ). This is a contribution of (37±12)% to the 450 µm background.