The location of gamma-ray emission in the jets of blazars is currently controversial. Recent multiwavelength campaigns along with VLBA studies have shown an association of the majority of gamma-ray events with disturbances propagating down the parsec-scale jet. This indicates that the locations of most gamma-ray flares lie beyond the broad line region (BLR), perhaps on scales comparable to the size of the dusty torus. On the other hand, external Compton models in which gamma-ray emission is limited to sites inside the BLR have been used to explain the high-energy emission of many blazars. Understanding the impact of all three external seed photon fields, namely the accretion disk, the BLR, and the dusty torus, on the evolution of the spectral energy distribution (SED) can be used as an important tool for relating the location of a particular gamma-ray flare to its multiwavelength properties.
Here, we use a multi-zone time-dependent leptonic jet model, with radiation feedback, to address this aspect of blazar jet emission. We let the system evolve to distances beyond the BLR. We explore the effects of varying the contribution of the disk and BLR on the resultant seed photon field and their effect on the simulated SED of a typical blazar to gain insight on how the multiwavelength characteristics depend on the location of the gamma-ray emission region. This research was supported in part by NASA through Fermi grants NNX10AO59G, NNX11AQ03G, and NNX12AO59G.