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1998AJ....115.1295K - Astron. J., 115, 1295-1318 (1998/April-0)
Sub-milliarcsecond imaging of quasars and active galactic nuclei.
KELLERMANN K.I., VERMEULEN R.C., ZENSUS J.A. and COHEN M.H.
Abstract (from CDS):
Most of the sources we have observed show the canonical core-jet morphology with structure somewhat characteristic of the jets seen on arcsecond scales with the Very Large Array and Westerbork telescopes. The milliarcsecond jets generally appear one-sided, but two-sided structure is often found in lower luminosity radio galaxies and in high-luminosity quasars with gigahertz-peaked spectra. In many cases there is significant curvature, sometimes up to 90° or more, particularly close to the core. In other cases the jets have a more gradual curvature. In some sources there are multiple bends or twists along the jet, suggestive of a three-dimensional curved structure. Many of the jets may be described by a small number of apparently discrete components, but in other cases there appears to be a monotonically decreasing distribution of radio emission. Usually the structure is unresolved along the direction perpendicular to the jet, but a few sources have broad plumes. Much of the visible parsec-scale structure in compact radio sources can probably be explained as the projection of a relativistic beamed, twisted jet, which appears bright at those positions where it approaches the viewer. In some low-luminosity radio galaxies, the structure appears more symmetric at 2 cm than at longer wavelengths. The apparent long-wavelength asymmetry in these sources is probably due to absorption by intervening ionized material. A few sources contain only a single component, with any secondary feature at least 1000 times weaker. Peak rest-frame brightness temperatures are typically of the order of 1011-1012 K, with no evidence for any excess over the limit of 1012 K expected from inverse Compton cooling. We find no obvious correlation of radio morphology and the detection of gamma-ray emission by EGRET.
Abstract Copyright: ∼
Journal keyword(s): Galaxies: Active - Galaxies: Jets - Galaxies: Nuclei
Simbad objects: 131
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