The Connection between Radio and Gamma-ray Emission in Active Galactic
  Nuclei
  Radio and gamma-ray emission from active galactic nuclei (AGN) are thought to
share a common origin, related to the ejection phenomena in the vicinity of
supermassive black holes. Thanks to its sensitivity, surveying capability, and
broad energy range, the Large Area Telescope (LAT) onboard the Fermi Gamma-ray
Space Telescope has permitted us to discover and characterize a huge number of
extragalactic gamma-ray sources. Similarly to what was found by EGRET, these
sources are typically associated with blazars, characterized by significant
radio emission and flat spectrum. The radio luminosity distribution is extended
over 7 orders of magnitudes, with flat spectrum radio quasars clustered at
higher powers and BL Lacs more scattered; the average spectral index is
consistent with alpha=0, although a few remarkable sources have alpha>0.5. A
comparison of the radio flux density and the gamma-ray photon flux is
presented, although claims on its significance require a detailed discussion
and Monte Carlo simulations which will be presented in a future paper.
