Detection of the cosmic infrared background at 2.2 and 3.5 microns using DIRBE observations

We compare data from the Diffuse Infrared Background Experiment (DIRBE) on COBE to the model of the infrared sky provided by Wainscoat and colleagues in 1992. The model is first compared with broadband K (2.2 mum) star counts . Its success at K band lends credence to its physical approach, which is e xtrapolated to the L band (3.5 mum). We have analyzed the histograms of the pixel-by-pixel intensities in the 2.2 and 3.5 mum maps from DIRBE after su btracting the zodiacal light. The shape of these histograms agrees quite we ll with the histogram shape predicted using the Wainscoat model of the infr ared sky, but the predicted histograms must be displaced by a constant inte nsity in order to match the data. This shift is the cosmic infrared backgro und, which is 16.9 +/- 4.4 kJy sr(-1) or 23.1 +/- 5.9 nW m(-2) sr(-1) at 2. 2 mum and 14.4 +/- 3.7 kJy sr(-1) or 12.4 +/- 3.2 nW m(-2) sr(-1) at 3.5 mu m. Combining our near-IR results with the far-IR background detected by Hau ser and colleagues in 1998 suggests that roughly half of the radiation prod uced by galaxies is absorbed by dust and reradiated in the far-IR.