Amanda successfully defended her PhD Proposal on October 11, 2011.
TITLE:
A DIAGNOSTIC TEST FOR DETERMINING THE LOCATION OF THE GEV EMISSION IN
POWERFUL BLAZARS
ABSTRACT:
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.