Fine structure of the BL Lac object 1803+784 |
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| Authors: | L I Matveyenko S Britzen J A Zensus |
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| Institution: | (1) Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia;(2) Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany |
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| Abstract: | We have investigated the superfine structure of the BL Lac object 1803+784, determined the ejector location, the helical structure of the jet, its parameters and relationship to the precession and nutation of the ejector rotation axis, and established the relationship to the periods of enhanced nuclear activity. The multimode precession is shown to be produced by the reactive action of the ejected relativistic plasma flow. The visibility of helix-structure fragments is determined by the transparency of the surrounding thermal plasma—the cocoon wall. The absorption in the cocoon wall has been found to depend on the distance from the core. The absorption of the synchrotron radio emission from the ejector region at 18 cm reaches ～30 dB. The spectra of the compact components located near the core have a low-frequency cutoff that is determined by the reabsorption of the synchrotron emission and by the absorption in the cocoon wall. The spectral index of the low-frequency part is α = 3.1–4.2. |
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| Keywords: | AGN ejector jet component spectra absorption |
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