http://arxiv.org/abs/1412.4777
The propagation of TeV gamma rays can be strongly modified by B-field induced conversion to axion-like particles. The conversion rate depends on the photon dispersion relation which, at such high energies, is dominated by the B-field itself through the QED photon-photon interaction. However, ambient photons also contribute and the cosmic microwave background (CMB) dominates when B < 3.25 micro-Gauss. We determine the photon-photon refractive index for all energies and find that, in intergalactic space, the CMB dominates for dispersion, whereas for absorption by gamma+gamma->electron+positron it is the extra-galactic background light. Local radiation fields, e.g., the galactic star light, can be more important for dispersion than the CMB.
A. Dobrynina, A. Kartavtsev and G. Raffelt
Wed, 17 Dec 14
56/67
Comments: 5 pages, 3 figures
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