TANAMI monitoring of Centaurus A (Müller et al.)

Vol. 569
In section 10. Planets and planetary systems

TANAMI monitoring of Centaurus A: The complex dynamics in the inner parsec of an extragalactic jet

by C. Müller, M. Kadler, R. Ojha, et al. A&A 569, A115


VLBI monitoring has revealed striking structures on subparsec scales in the radio jet of Centaurus A (Cen A). The proper motions over 3.5 years of individual jet components have been followed every six months at 8.4 GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa, complemented by quasi-simultaneous 22.3 GHz observations. They show apparent component speeds within 0.1c to 0.3c, with some varying higher speed differential motions superposed on a long-term stable feature. The interpretation is in terms of a spine-sheath structure with a faster inner jet and downstream acceleration where the jet becomes optically thin. The flow appears to be interrupted by an obstacle causing a local decrease in surface brightness and circumfluent jet behavior. A jet-star interaction could explain these features.