Issue |
A&A
Volume 406, Number 1, July IV 2003
|
|
---|---|---|
Page(s) | 43 - 50 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20030523 | |
Published online | 17 November 2003 |
The Faraday screen near the nucleus of the CSS quasar 3C 138
1
National Radio Astronomy Observatory (The National Radio Astronomy Observatory (NRAO) is operated by Associated Universities Inc., under cooperative agreement with the National Science Foundation.) , 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
2
Istituto di Radioastronomia del CNR, Via P. Gobetti 101, 40129 Bologna, Italy
3
Dipartimento di Fisica, Universitá di Bologna, via Irnerio 46, 40126 Bologna, Italy
4
Netherlands Foundation for Research in Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
5
Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands
6
Sterrenwacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands
7
NRAL-Jodrell Bank, University of Manchester, Macclesfield Cheshire, SK11 9DL, UK
Corresponding author: W. D. Cotton, bcotton@nrao.edu
Received:
15
January
2003
Accepted:
6
April
2003
Compact Steep Spectrum (CSS) sources are known to show strong optical
line emission [CITE] which is generally considered to
be due to the interaction between the radio jet and the ISM.
This argument is strengthened by the HST observations of [CITE]
which show this emission is frequently associated with the radio jet.
Previous observations of the CSS quasar 3C 138 [CITE] have
shown that the bulk of the jet has very low amounts of Faraday
rotation whereas the inner jet shows very high Faraday rotation
( rad m-2).
The inner jet is dominated by moving components which allows observing
the fine scale of the Faraday screen as the components move behind
it.
We report the results of such a monitoring campaign which indicated
that there is structure in the Faraday screen on the pc and possibly
sub pc scale.
Motions of the polarized component slowed dramatically during the
course of these observations, limiting the region probed.
The observations also strongly suggest that the polarized emission
from the inner jet is seen through limited holes in a dense Faraday
screen.
In this case, the observed variations in Faraday rotation are possibly
the result of jet–ISM interactions.
Key words: polarization / galaxies: quasars: individual: 3C 138 / galaxies: jets / galaxies: nuclei / radio continuum: galaxies
© ESO, 2003
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