Date of Award
Master of Science
Physics and Astronomy
As Very High Energy (VHE) photons travel through the extragalactic background light (EBL), they will interact and generate electron and positron pairs via pair production. The newly produced electrons and positrons will Inverse-Compton scatter the background soft photons to secondary gamma-rays in the process of electromagnetic cascading. The intensity of a cosmological population emitting at VHEs will be attenuated at the highest energies due to absorption and enhanced at lower energies by the resulting cascade. We calculate the cascade radiation created by VHE photons produced by blazars and investigate the effects of cascades on the observed intensity of individual blazars. We find that the cascade radiation greatly enhances the observed intensity at the observational energy range. The prominence of the resulting features depends on the intrinsic spectral index and the location of the source. We
additionally calculate the cascade radiation from several sources with distinct spectral index and cosmological positions. Finally, we discuss the implications that this analysis could have for the prediction of sourse spectrum with the observational data from VERITAS and FERMI.
Fang, Ke, "Contribution to individual blazar spectrum from the cascade of very-high energy gamma rays" (2010). Graduate Theses and Dissertations. 11461.