Bibcode
Steenbrugge, K. C.; Blundell, K. M.; Pyrzas, S.
Bibliographical reference
Astronomy and Astrophysics, Volume 563, id.A131, 7 pp.
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3
2014
Journal
Citations
4
Refereed citations
4
Description
Context. Cygnus A, as the nearest powerful FR II radio galaxy, plays an
important role in understanding jets and their impact on the surrounding
intracluster medium. Aims: We explain why the nucleus is observed
superposed onto the eastern lobe rather than in between the two lobes,
and why the jet and counterjet are non-colinear. Methods: We made
a comparative study of the radio images at different frequencies of
Cygnus A, in combination with the published results on the radial
velocities in the Cygnus A cluster. Results: From the morphology
of the inner lobes we conclude that the lobes are not interacting with
one another, but are well separated, even at low radio frequencies. We
explain the location of the nucleus as the result of the proper motion
of the galaxy through the cluster. The required proper motion is of the
same order of magnitude as the radial velocity offset of Cygnus A with
the sub-cluster it belongs to. The proper motion of the galaxy through
the cluster likely also explains the non-colinearity of the jet and
counterjet.