The Core Dominance Parameter Of AGNs And ?-ray Detection

In this paper, based on an archive sample of 542 extragalactic radio sources with available core dominance parameter, radio core luminosity and flux, redshift, we identified 80 radio sources with corresponding ?-ray emission, and investigated the correlations between core dominance parameter and multiple parameters.Through the comparison of 80 Fermi sources(22 BL Lacs, 44 quasars,14 galaxies) and 462 non-Fermi sources(5 BL Lacs, 171 quasars, 286galaxies), we found that: 1) the Fermi sources have larger mean R values and smaller redshifts. 2) the Fermi sources have on average higher core luminosity. These results suggest that the Fermi sources should be more compact, and beaming effect should play a crucial role for the detection of ?-ray emission. While we can not exclude the possibility that their intrinsic flux might also plays a role. Meanwhile, the Fermi sources have systematically larger radio flux than non-Fermi sources at fixed core dominance parameter and redshift, the results indicate the stong correlation between ?-ray emission and radio emission. Together with the result in Wu et al.(2014) which shows the Fermi BL Lacs have systematically larger radio flux than non-Fermi BL Lac at fixed Doppler factor. It fully illustrated the non-Fermi sources not only have the low intrinsic radio core flux than Fermi sources, but also have the low intrinsic ?-ray flux.This all indicate the closely correlation between radio and ?-ray emission. The results further indicate the radio and ?-ray emission might come from the same radiation area for our sample of AGNs.