Is there an unaccounted excess Extragalactic Cosmic Radio Background?
  Analyses of measurements of the distribution of absolute brightness
temperature over the radio sky have led recently to suggestions that there
exists a substantial unexplained extragalactic radio background. Consequently,
there have been numerous attempts to place constraints on plausible origins for
the `excess'. We suggest here this expectation of a large extragalactic
background, over and above that contributed by the sources observed in the
surveys, is based on an extremely simple geometry adopted to model the Galactic
emission and the procedure adopted in the estimation of the extragalactic
contribution. In this paper, we derive the extragalactic radio background from
wide-field radio images by using a more realistic modeling of the Galactic
emission and decompose the sky maps at 150, 408, and 1420 MHz into anisotropic
Galactic and isotropic extragalactic components. The anisotropic Galactic
component is assumed to arise from a highly flattened spheroid representing the
thick disc, embedded in a spherical halo, both centered at the Galactic center,
along with Galactic sources, filamentary structures, Galactic loops and spurs.
All components are constrained to be positive and the optimization scheme
minimizes the sky area occupied by the complex filaments. We show that in
contrast to the simple modeling of the Galactic emission as a plane parallel
slab, the more realistic modeling yields estimates for the uniform
extragalactic brightness that is consistent with expectations from known
extragalactic radio source populations.
