Derivation of a large isotropic diffuse sky emission component at 1.25
  and 2.2um from the COBE/DIRBE data
  Using all-sky maps obtained with COBE/DIRBE, we reanalyzed the diffuse sky
brightness at 1.25 and 2.2 um, which consists of zodiacal light, diffuse
Galactic light (DGL), integrated starlight (ISL), and isotropic emission
including the extragalactic background light. Our new analysis including an
improved estimate of the DGL and the ISL with the 2MASS data showed that
deviations of the isotropic emission from isotropy were less than 10% in the
entire sky at high Galactic latitude (|b|>35). The result of our analysis
revealed a significantly large isotropic component at 1.25 and 2.2 um with
intensities of 60.15 +/- 16.14 and 27.68 +/- 6.21 nWm-2sr-1, respectively. This
intensity is larger than the integrated galaxy light, upper limits from
gamma-ray observation, and potential contribution from exotic sources (i.e.,
Population III stars, intrahalo light, direct collapse black holes, and dark
stars). We therefore conclude that the excess light may originate from the
local universe; the Milky Way and/or the solar system.
