Determining the ratio of the jet to the unbeamed luminosities for γ-ray blazars

Abstract

ABSTRACT The spectacular observational phenomena lying in blazars can be well explained and described by the relativistic beaming effect that the emission in the jet is highly boosted along the line of sight to observers. Aiming to reveal the intrinsic emission core dominance in γ-ray loud blazars, we collect a large sample including 226 blazars with available superluminal motion data and radio core-dominance parameters at 5 GHz, and calculate a crucial parameter, R⊥, defined as the ratio of the luminosity in the jet to the unbeamed luminosity when the viewing angle comes up to 90°. R⊥ is a better parameter than the well-known core-dominance parameter, R, to reveal more intrinsic physical properties behind the prominent observational characteristics within blazars. We primarily ascertain the updated median value of R⊥ = 0.032 at 5 GHz, illustrating around 97 per cent of the total radio emission are dominated by the jets in γ-ray loud blazars. We also make further discussion on the physical difference in BL Lacertae objects and flat-spectrum radio quasars.