Multi-frequency & Multi-epoch VLBI study of Cygnus A

2003/09/15 by U. Bach, M. Kadler, Bach, U. +11
Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #Gamma-ray bursts and supernovae #Radio Astronomy Observations and Technology #astro-ph

paper · pdf · doi:10.48550/arxiv.astro-ph/0309403

To be published in "Future Directions in High Resolution Astronomy" (A Celebration of the 10th Anniversary of the VLBA), held June 8 - 12, 2003, in Socorro, New Mexico, USA; ASP Conference Series. 5 pages, 4 figures

arxiv created 2003/09/15 · openalex publication_date 2003/09/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We present the first multi-frequency phase-referenced observations of Cygnus A done with the VLBA at 15 and 22 GHz. 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 15 GHz VLBA data we accurately derive the jet and counter-jet kinematics. For the inner jet (r <= 5 mas) we measure motions of beta_app ~ 0.2-0.5 h^-1 and on the counter-jet side we find beta_ app ~ 0.03+-0.02 h^-1. We discuss the jet velocities within the unified jet model.

Related

• Spectral Properties of the Core and the VLBI-Jets of Cygnus A
• Proper motion in Cygnus A
• High resolution mm-VLBI imaging of Cygnus A
• Resolving the jet in Cygnus A
• VLBI constraints on the "jet-line" of Cygnus X-1