UBC Theses and Dissertations
Contribution to the diffuse radio background from extragalactic radio sources Vernstrom, Tessa
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 n = 150MHz, 325MHz, 408MHz, 610MHz, 1:4GHz, 4:8GHz, and 8:4GHz our calculated contributions to the background sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032, 0.0059 K, respectively. We then compare our results to absolute measurements from the 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. We present preliminary results of investigating this new population by use of signal stacking. By stacking onto a very deep 1:4GHz radio map at source positions determined in the infrared and optical we hope to be able to see evidence of this population that would be too faint to be seen individually. Results are currently inconclusive. Future work will consist of modelling radio luminosity functions and new observations with the Extended VLA to continue to search for what may be causing this excess emission.
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