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Paper: VLBI Properties of Gamma-Ray Blazars
Volume: 300, Radio Astronomy at the Fringe
Page: 89
Authors: Jorstad, S.G.; Marscher, A.P.
Abstract: We have completed a program in which we monitored a sample of γ-ray blazars with the VLBA at 22 and 43 GHz. The distribution of apparent speeds, determined for 23 quasars and 10 BL Lac objects, reveals that the majority of superluminal components have velocities exceeding 10c in both γ-ray quasars and BL Lac objects. On average, EGRET-detected blazars are characterized by highly relativistic jets with Lorentz factor Γ ∼ 20, viewing angle Θ ∼ 1° - 2°, opening half-angle α ∼ 1°, and Doppler factor δ ∼ 25 - 30. However, more intensive and sensitive surveys are needed to determine whether the Lorentz factor, and viewing and opening angles are constant parameters of the jet or, if not, the ranges of the variability of these parameters for a typical source.
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