Visit ASIAA Homepage Deadline: February 15, 2016
M87 Workshop: Towards the 100th Anniversary of the Discovery of Cosmic Jets
May 23-27, 2016
Taipei, Taiwan

Invited Presentation

Proper Motions and Variability in the M87 Jet

Author(s): John Biretta (Eureka Scientific/STScI)

Presenter: John Biretta (Eureka Scientific/STScI)

Multi-epoch observations of the M87 jet have been made by several teams in an effort to study its kinematics and variability. Outward motion at apparent superluminal speeds have been reported in jet regions from sub-pc to kpc-scales in radio and optical data for M87. The jet structure and kinematics are complex -- stationary and sub-luminal features are also seen throughout the jet, and often in close association with superluminal features. The fastest superluminal speeds are in a compact region called HST-1 located ~0.9 arcsecond (~70 pc) from the nucleus -- speeds up to ~6c are seen in HST data for several small knots, while the VLBA finds speeds up to ~4c. Both optical and radio data show these fast knots being emitted by slower up-stream features. HST-1 was also the site of a large optical to X-ray outburst peaking in 2005. At larger distances from the nucleus, the observed local maximum speeds decrease with increasing distance. Knots D, E, & F (200 - 700 pc distance) show maximum speeds from ~4c to ~2c, and the bright A-B-C complex (1 - 1.5 kpc distance) shows maximum speeds from ~2c to ~c. While the largest velocities are directed away from the nucleus, many of the slower features show significant transverse velocities with some velocities directed up to ~40 degrees from the jet axis. Nearer the nucleus (<30 pc distance) VLBA observations show a relatively smooth, limb-brightened jet -- the brightest structures in this region appear stationary or move slowly (<0.4c), though speeds of 1c to 2c are seen in a few faint features. We review these and other results related to proper motions, as well as their implications for jet physics.

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