Correlation between Fermi/LAT gamma-ray and 37 GHz radio properties of
  northern AGN averaged over 11 months
  Although the Fermi mission has increased our knowledge of gamma-ray AGN, many
questions remain, such as the site of gamma-ray production, the emission
mechanism, and the factors that govern the strength of the emission. Using data
from a high radio band, 37 GHz, uncontaminated by other radiation components
besides the jet emission, we study these questions with averaged flux densities
over the the first year of Fermi operations. We look for possible correlations
between the 100 MeV - 100 GeV band used by the Fermi satellite and 37 GHz radio
band observed at the Aalto University Metsahovi Radio Telescope, as well as for
differences between the gamma-ray emission of different AGN subsamples. We use
data averaged over the 1FGL period. Our sample includes 249 northern AGN,
including a complete sample of 68 northern AGN with a measured average flux
density exceeding 1 Jy. We find significant correlation between both the flux
densities and luminosities in gamma and radio bands. The Fermi luminosity is
inversely correlated with the peak frequency of the synchrotron component of
the AGN spectral energy distributions. We also calculate the gamma dominances,
defined as the ratio between the gamma and radio flux densities, and find an
indication that high-energy blazars are more gamma-dominated than low-energy
blazars. After studying the distributions of gamma and radio luminosities, it
is clear that BL Lacertae objects are different from quasars, with
significantly lower luminosities. It is unclear whether this is an intrinsic
difference, an effect of variable relativistic boosting across the synchrotron
peak frequency range, or the result of Fermi being more sensitive to hard
spectrum sources like BL Lacertae objects. Our results suggest that the gamma
radiation is produced co-spatially with the 37 GHz emission, i.e., in the jet.
