Parsec-scale jets and tori in seyfert galaxies

A. L. Roy, J. M. Wrobel, A. S. Wilson, James S. Ulvestad, Carole Mundell, R. P. Norris, T. P. Krichbaum, H. Falcke, E. J. M. Colbert

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding


Active galaxies tend to be powerful or weak radio sources, and we still do not understand the underlying cause. Perhaps the engine is the same in both systems and the jet gets disrupted by dense interstellar medium in radio-quiet objects, or else the difference is intrinsic with jet power scaling with black hole spin. To distinguish, one can look for signs of interaction between the jet and the narrow-line region, and to measure the jet speed close to the jet base, before environmental effects become important. We find one-sided parsec-scale jet structures in Mrk 348, Mrk 231, NGC 4151, and NGC 5506 using VLBI, and we measure low jet speeds (typically <= 0.25 c). The one-sidedness probably is not due to Doppler boosting, but rather is probably free-free absorption. Plasma conditions required to produce the absorption are Ne >= 2 × 105 cm-3 assuming a path length of 0.1 pc, typical of that expected at the inner edge of the obscuring torus.
Original languageEnglish
Title of host publicationGalaxies and their Constituents at the Highest Angular Resolutions
Subtitle of host publicationProceedings of IAU Symposium #205, held 15-18 August 2000
EditorsR. T. Schilizzi
Publication statusPublished - Jan 2001


Dive into the research topics of 'Parsec-scale jets and tori in seyfert galaxies'. Together they form a unique fingerprint.

Cite this