Clustering of the Diffuse Infrared Light from the [ITAL]COBE[/ITAL] DIRBE Maps: An All-Sky Survey of [ITAL]C[/ITAL](0)

We measure the smoothness of the infrared sky using the COBE DIRBE maps, andobtain interesting limits on the production of the diffuse cosmic infraredbackground (CIB) light by matter clustered like galaxies. The predictedfluctuations of the CIB with the DIRBE beam size of 0.7\deg\ are of the orderof 10\%, and the maps are smooth at the level of $\delta\nu I_\nu \sim $ a few\nwm2sr rms from 2.2 to 100 \um. The lowest numbers are achieved at mid- tofar-IR where the foreground is bright but smooth; they are$\sqrt{C(0)}$$\leq$$(1-1.5)$ \nwm2sr at $\lambda=$ 10-100 \um. If the CIB comesfrom clustered matter evolving according to typical scenarios, then thesmoothness of the maps implies CIB levels less than $\sim (10-15) $ \nwm2srover this wavelength range.Comment: 15 pages (LATEX) with 2 figures and 1 plate; Ap. J. Letters, in pres