Gamma-ray-loud blazars and beaming

We study the entire sample of quasars detected above 100 MeV (by the EGRET instrument), on board CGRO. We find that the gamma-ray luminosity correlates better with the radio luminosity than with the optical or X-ray luminosity, even if the different variability behaviour indicates different emission regions. A strong correlation is also found between the broad-band spectral indices alpha_ro, connecting the radio and the optical fluxes, and alpha_ogamma, connecting the optical and the gamma-ray fluxes. The gamma-ray luminosity in BLLac objects is on average much less dominant than in the other sources. With the requirement that the gamma-rays do not interact with X-rays (assumed cospatial) through photon-photon collisions, we calculate the lower limit on the Doppler or beaming factor of the gamma-ray emission region for a large fraction of the sources of the sample, finding that relativistic motion is required in all cases.