An Empirical Decomposition of Near–ir Emission into Galactic and Extragalactic Components

We decompose the COBE/DIRBE observations of the near–IR sky brightness (minus zodiacal light) into Galactic stellar and interstellar medium (ISM) components and an extragalactic background. This empirical procedure allows us to estimate the 4.9 μm cosmic infrared background (CIB) as a function of the CIB intensity at shorter wavelengths. A weak indication of a rising CIB intensity at λ > 3.5 μm hints at interesting astrophysics in the CIB spectrum, or warns that the foreground zodiacal emission may be incompletely subtracted. Subtraction of only the stellar component from the zodiacal–light–subtracted all–sky map reveals the clearest 3.5 μm ISM emission map, which is found to be tightly correlated with the ISM emission at far–IR wavelengths. Subject headings: diffuse radiation — dust, extinction — Galaxy: stellar content — infrared: galaxies — infrared: ISM — infrared: stars