| |
 |
| Paper: |
Multi-Frequency & Multi-Epoch VLBI Study of Cygnus A |
| Volume: |
340, Future Directions in High Resolution Astronomy: The 10th Anniversary of the VLBA |
| Page: |
30 |
| Authors: |
Bach, U.; Kadler, M.; Krichbaum, T.P.; Middelberg, E.; Alef, W.; Witzel, A.; Zensus, J.A. |
| Abstract: |
We present the first multi-frequency phase-referenced observations of Cygnus A done with the VLBA at 15 and 22GHz. We find a pronounced two-sided jet structure, with a steep spectrum along the jet and a highly inverted spectrum towards the counter-jet. The inverted spectrum and the frequency dependent jet to counter-jet ratio suggest an obscuring torus in front of the counter-jet. From 14 epochs of 15GHz VLBA data we accurately derive the jet and counter-jet kinematics. For the inner jet (r ≤ 5 mas) we measure motions of βapp ≈ 0.2 − 0.5 h−1 and on the counter-jet side we find βapp ≈ 0.03 ± 0.02 h−1. We discuss the jet velocities within the unified jet model. |
|
|
|
|
|
