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Variability and proper motion of x-ray knots in the jet of Centaurus A

Snios, Bradford; Wykes, Sarka; Nulsen, Paul E. J.; Kraft, Ralph P.; Meyer, Eileen T.; Birkinshaw, Mark; Worrall, Diana M.; Hardcastle, Martin J.; Roediger, Elke; Forman, William R.; Jones, Christine


Bradford Snios

Sarka Wykes

Paul E. J. Nulsen

Ralph P. Kraft

Eileen T. Meyer

Mark Birkinshaw

Diana M. Worrall

Martin J. Hardcastle

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Dr Elke Roediger
Senior Lecturer/ Director of Studies for Physics

William R. Forman

Christine Jones


We report results from Chandra observations analyzed for evidence of variability and proper motion in the X-ray jet of Centaurus A. Using data spanning 15 years, collective proper motion of 11.3±3.3 mas yr−1, or 0.68±0.20c, is detected for the fainter X-ray knots and other 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 27% 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 μG for each of their magnetic field strengths. Adiabatic expansion can 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.

Journal Article Type Article
Publication Date Feb 5, 2019
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 871
Issue 2
Article Number 248
APA6 Citation Snios, B., Wykes, S., Nulsen, P. E. . J., Kraft, R. P., Meyer, E. T., Birkinshaw, M., …Jones, C. (2019). Variability and proper motion of x-ray knots in the jet of Centaurus A. The Astrophysical journal, 871(2), doi:10.3847/1538-4357/aafaf3
Keywords Galaxies: active; Galaxies: individual (Centaurus A); Galaxies: jets; X-rays: galaxies
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© 2019. The American Astronomical Society. All rights reserved.

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