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2004ApJ...609..539K - Astrophys. J., 609, 539-563 (2004/July-2)
Sub-milliarcsecond imaging of quasars and active galactic nuclei. III. Kinematics of parsec-scale radio jets.
KELLERMANN K.I., LISTER M.L., HOMAN D.C., VERMEULEN R.C., COHEN M.H., ROS E., KADLER M., ZENSUS J.A. and KOVALEV Y.Y.
Abstract (from CDS):
The observed distribution of linear velocities is not consistent with any simple ballistic model. Either there is a rather broad range of Lorentz factors, a significant difference between the velocity of the bulk relativistic flow and the pattern speed of underlying shocks, or a combination of these options. Assuming a ballistic flow, comparison of observed apparent velocities and Doppler factors computed from the timescale of flux density variations is consistent with a steep power-law distribution of intrinsic Lorentz factors, an isotropic distribution of orientations of the parent population, and intrinsic brightness temperatures about an order of magnitude below the canonical inverse Compton limit. It appears that the parent population of radio jets is not dominated by highly relativistic flows, and contrary to the assumption of simple unified models, not all sources have intrinsic speeds close to c.
Usually, the observed jet flow is in the general direction of an established jet. However, many jets show significant bends and twists, where the observed motions are nonradial but are aligned with the local jet direction, suggesting that the jet flow occurs along preexisting bent channels. In a few cases we have observed a clear change in the direction of a feature as it flows along the jet. Radio jets that are also strong gamma-ray sources detected by EGRET appear to have significantly faster speeds than the non-EGRET sources, consistent with the idea that gamma-ray sources have larger Doppler factors than non-gamma-ray sources. Sources at high redshift have systematically lower angular speeds than low-redshift jets, consistent with standard cosmologies.
Abstract Copyright: ∼
Journal keyword(s): Galaxies: Active - Galaxies: Jets - Galaxies: Quasars: General - Radio Continuum: Galaxies
VizieR on-line data: <Available at CDS (J/ApJ/609/539): table1.dat table2.dat>
Nomenclature: Table 2: [KLH2004] HHMM+DDd A N=200.
CDS comments: Table 2: 0238-084 WNN: see 2003A&A...401..113V ([VRK2003])
Simbad objects: 132
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