Active galactic nuclei ( AGNs ) have been attracting research attention due to their special observable properties .
Specifically , a majority of AGNs are detected by Fermi-LAT missions , but not by Fermi-LAT , which raises the question of weather any differences exist between the two .
To answer this issue , we compile a sample of 291 superluminal AGNs ( 189 FDSs and 102 non-FDSs ) from available multi-wavelength radio , optical , and X-ray ( or even \gamma -ray ) data and Doppler factors and proper motion ( \mu ) ( or apparent velocity ( \beta _ { app } ) ) ; calculated the apparent velocity from their proper motion , Lorentz factor ( \Gamma ) , viewing angle ( \phi ) and co-moving viewing angle ( \phi _ { co } ) for the sources with available Doppler factor ( \delta ) ; and performed some statistical analyses for both types .
Our study indicated that 1 .
In terms of average values , FDSs have higher proper motions ( \mu ) , apparent velocities ( \beta _ { app } ) , Doppler factor ( \delta ) , Lorentz factor ( \Gamma ) , and smaller viewing angle ( \phi ) .
Nevertheless , there is no clear difference in co-moving viewing angles ( \phi _ { co } ) .
The results reveal that that FDSs show stronger beaming effect than non-FDSs .
2 .
In terms of correlations : ( 1 ) Both sources show positive , mutually correlated fluxes , which become closer in de-beamed fluxes ; ( 2 ) With respect to apparent velocities and \gamma -ray luminosity , there is a tendency for the brighter sources to have higher velocities ; ( 3 ) With regard to viewing angle and observed \gamma -ray luminosity , { log } \phi = - ( 0.23 \pm 0.04 ) { log } L _ { \gamma } + ( 11.14 \pm 1.93 ) , while for the co-moving viewing angle and the intrinsic \gamma -ray luminosity , { log } \phi _ { co } = ( 0.09 \pm 0.01 ) { log } L _ { \gamma } ^ { in } - ( 1.73 \pm 0 % .48 ) .
These correlations show that the luminous \gamma -ray sources have smaller viewing angles and a larger co-moving viewing angle , which indicate a stronger beaming effect in \gamma -ray emissions .