Variability and Proper Motion of X-ray Knots in the Jet of Centaurus A
Abstract
We report results from Chandra observations analyzed for evidence of variability and proper motion in the X-ray jet of Centaurus A. Using 15 years of archival images, an average proper motion of 11.3 mas yr-1, or 0.68c, is detected for both the X-ray knots and the substructure present within the jet. The three brightest knots (AX1A, AX1C, and BX2) are found to be stationary to an upper limit of 0.10c. Brightness variations up to 55% are detected for several X-ray knots in the jet. For the fading knots BX2 and AX1C, the changes in spectral slope expected to accompany synchrotron cooling are not found, ruling it out and placing upper limits of 80 and 160 μG, respectively, on their magnetic field strengths. Adiabatic expansion is shown to account for the observed decreases in brightness. Constraints on models for the origin of the knots are established. Jet plasma overrunning an obstacle is favored as the generator of stationary knots, while moving knots are likely produced either by internal differences in jet speed or the late stages of jet interaction with nebular or cloud material.
- Publication:
-
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23321301S