A Connection Between Apparent VLBA Jet Speeds and Initial Active
  Galactic Nucleus Detections Made by the Fermi Gamma-ray Observatory
  In its first three months of operations, the Fermi Gamma-Ray Observatory has
detected approximately one quarter of the radio-flux-limited MOJAVE sample of
bright flat-spectrum active galactic nuclei (AGNs) at energies above 100 MeV.
We have investigated the apparent parsec-scale jet speeds of 26 MOJAVE AGNs
measured by the Very Long Baseline Array (VLBA) that are in the LAT bright AGN
sample (LBAS). We find that the gamma-ray bright quasars have faster jets on
average than the non-LBAS quasars, with a median of 15 c, and values ranging up
to 34 c. The LBAS AGNs in which the LAT has detected significant gamma-ray flux
variability generally have faster jets than the nonvariable ones. These
findings are in overall agreement with earlier results based on nonuniform
EGRET data which suggested that gamma-ray bright AGNs have preferentially
higher Doppler boosting factors than other blazar jets. However, the relatively
low LAT detection rates for the full MOJAVE sample (24%) and previously known
MOJAVE EGRET-detected blazars (43%) imply that Doppler boosting is not the sole
factor that determines whether a particular AGN is bright at gamma-ray
energies. The slower apparent jet speeds of LBAS BL Lac objects and their
higher overall LAT detection rate as compared to quasars suggest that the
former are being detected by Fermi because of their higher intrinsic (unbeamed)
gamma-ray to radio luminosity ratios.
