Size-Luminosity scaling and Inverse Compton Seed Photons in Blazars

We present preliminary results of our work on blazar unification. We assume that all blazars have a broad line region (BLR) and that the size of the BLR scales with the power of the source in a manner similar to that derived through reverberation mapping in radio quiet active galactic nuclei (AGNs). Using a self-consistent emission model that includes particle acceleration we show that according to this scaling, in weak sources like MKN 421, the inverse Compton (IC) scattering losses are dominated by synchrotron-self Compton scattering (SSC), while in powerful sources, like 3C 279, they are dominated by external Compton (EC) scattering of BLR photons. In agreement with other workers, we show that even in the powerful sources that are dominated by EC scattering, the hard X-ray emission is due to SSC. Finally, we show that this scaling reproduces well the observed sequence of blazar properties with luminosity.