Blazar Compton efficiencies: Fermi, external photons and the Sequence
  The Fermi-LAT survey provides a large sample of blazars selected on the
strength of their inverse Compton emission. We cross-correlate the first
Fermi-LAT catalogue with the CRATES radio catalogue and use this sample to
investigate whether blazar gamma-ray luminosities are influenced by the
availability of external photons to be up-scattered. Using the 8.4 GHz flux
densities of their compact radio cores as a proxy for their jet power, we
calculate their Compton Efficiency parameters, which measure the ability of
jets to convert power in the form of ultra-relativistic electrons into Compton
gamma-rays. We find no clear differences in Compton efficiencies between BL Lac
objects and FSRQs and no anti-correlation between Compton efficiency and
synchrotron peak frequency. This suggests that the scattering of external
photons is energetically unimportant compared to the synchrotron self-Compton
process. These results contradict the predictions of the blazar sequence.
