Amanda successfully defended her PhD Proposal on October 11, 2011.
A DIAGNOSTIC TEST FOR DETERMINING THE LOCATION OF THE GEV EMISSION IN
An issue currently debated in the literature is how far from the black hole is the Fermi observed
GeV emission of powerful blazars emitted. Here we present a clear diagnostic tool for testing whether the GeV emission site is located within the sub-pc broad emission line (BLR) region or further out in the few pc scale molecular torus environment. Within the BLR the scattering takes place at the onset of the Klein-Nishina regime, causing the electron cooling time to become almost energy independent and as a result, the variation of high-energy emission is expected to be achromatic. Contrarily, if the blazar is outside the BLR, the expected GeV variability is energy-dependent and with amplitude increasing with energy. We demonstrate this using time-dependent numerical simulations of blazar variability, and propose to apply the diagnostic test using Fermi data. The proposed work holds the promise of settling this important issue.