Simulations, Modeling, and Searches for Pair Conversion Halos around Active Galactic Nuclei
Pair halos would be observational evidence of interactions between electromagnetic cascades in the intergalactic medium and non-zero magnetic fields. If detected, they would represent a crucial probe into the evolution of our universe and potentially new physics at very early cosmological times. However, they are also expected to be extremely faint. In this thesis, we take a three-stage approach to examining pair halos. We determine the halo's spectral, spatial, and temporal morphology by building a detailed physical simulator of the pair halo process. We then use this understanding to build detection methods which rely on the unique spatial and temporal characteristics of the halo and its progenitor active galactic nucleus (AGN). Finally, we test one of these methods on data from the Fermi Large Area Telescope, determine its sensitivity to different halos, and predict the performance improvements needed to make detections with future instruments.