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Title: Is there an unaccounted for excess in the extragalactic cosmic radio background?
Authors: Subrahmanyan, Ravi
Cowsik, Ramanath
Keywords: Radio continuum
Issue Date: 10-Oct-2013
Publisher: IOP Sciences for The American Astronomical Society
Citation: Astrophysical Journal, 2013, Vol.776, p42
Abstract: Analyses of the distribution of absolute brightness temperature over the radio sky have recently led to suggestions that there exists a substantial unexplained extragalactic radio background. Consequently, there have been numerous attempts to place constraints on plausible origins of this "excess." We suggest here that 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 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 disk, embedded in a spherical halo, both centered at the Galactic center, along with Galactic sources, filamentary structures, and 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 with simple modeling of Galactic emission as a plane parallel slab, the more realistic modeling yields estimates for the uniform extragalactic brightness that are consistent with expectations from known extragalactic radio source populations.
Description: Restricted Access
ISSN: 0004-637X
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Copyright: 2013 American Astronomical Society, This article may be downloaded for personal use only. Any other use requires prior permission of the author and The American Astronomical Society
Appears in Collections:Research Papers (A&A)

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