The Diffuse Synchrotron Radio Background from Normal Spiral Galaxies in the Context of the ARCADE Excess
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In this thesis, the possibility that synchrotron radiation from cosmic ray electrons in normal spiral galaxies can account for the ARCADE excess is investigated. The ARCADE excess is an excess flux measured in the sky temperature at radio frequencies. It cannot be explained by any of the usual candidates for galactic or extra-galactic emission. Inspired by an article by Fornengo et al., where an origin in synchrotron radiation from electrons produced in dark matter annihilations or decays is proposed, the possibility that conventional synchrotron background from diffuse sources can be responsible is explored. After covering the necessary background material on cosmology, dark matter and radio frequency radiation, a simple model for the total synchrotron background from normal spiral galaxies is presented. The model has some free parameters that control the overall normalization. These parameters include the average synchrotron luminosity of a spiral galaxy and the redshift evolution of these sources. For somewhat optimistic values for these parameters, the model is found able to account for the excess. More constraining experimental data isrequired to make any conclusive judgments on the viability of the model.