Contribution to the diffuse radio background from extragalactic radio sources

• Published in: Monthly notices of the Royal Astronomical Society 2011-08, Vol.415 (4), p.3641-3648
• Main Authors: Vernstrom, T., Scott, Douglas, Wall, J. V.
• Format: Article
• Language: English
• Subjects: Arcades; Astronomy; Astrophysics; Brightness; Cosmology; Counting; diffuse radiation; Diffusion; Earth, ocean, space; Estimates; Exact sciences and technology; galaxies: statistics; Monte Carlo methods; Radio; Radio astronomy; radio continuum: galaxies; Radio galaxies; Stars & galaxies
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1111/j.1365-2966.2011.18990.x

We examine the brightness of the cosmic radio background (CRB) by comparing the contribution from individual source counts to absolute measurements. We use a compilation of radio counts to estimate the contribution of detected sources to the CRB in several different frequency bands. Using a Monte Carlo Markov chain technique, we estimate the brightness values and uncertainties, paying attention to various sources of systematic error. At ν= 150, 325, 408, 610, 1.4, 4.8 and 8.4 GHz, our calculated contributions to the background sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032 and 0.0059 K, respectively. We then compare our results to absolute measurements from the Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission (ARCADE 2) experiment. If the ARCADE 2 measurements are correct and come from sources, then there must be an additional population of radio galaxies, fainter than where current data are probing. More specifically, the Euclidean-normalized counts at 1.4 GHz have to have an additional bump below about 10 μJy.