Astron. Astrophys. Suppl. Ser. 143, 457-464
VLA polarimetry of two extended radio galaxies
W. Junor1 - F. Mantovani2 -
R. Morganti2,3 - L. Padrielli2
Send offprint request: F. Mantovani
Institute for Astrophysics, University of New Mexico, Albuquerque,
Istituto di Radioastronomia del CNR, Bologna, Italy
Australian Telescope National Facility, Epping, NSW 2121,
Received May 7, 1996; accepted February 25, 2000
Multi-wavelength VLA observations of two extended radio galaxies, 0235-197and 1203+043 are presented. There is some evidence from earlier
studies that these two sources exhibit low frequency (<1GHz) variability.
This work shows that both sources have linear polarizations, if any,
below the detection limits at 320 MHz,
so we cannot explain the variability as being due to
instrumental polarization effects as has been suggested for 3C 159.
Refractive scintillation may be the cause of the
variability in 0235-197. This would require the existence of a
bright, compact component in one of the hot spots seen in these
observations. This is not implausible but the resolution of this
observational program is insufficient to address that question.
The radio source 1203+043 lacks any bright compact
component thereby ruling out a refractive scintillation mechanism for
its variability. Consequently, it is possible that claims of
variability in this source are spurious. However, the 320MHz VLA
observations show that 1203+043 has an "X''-shaped radio structure.
This is a rare morphology for the brightness distribution of a radio
galaxy; the implications of this are examined.
Key words: galaxies: individual: 0235+197, 1203+043 -- techniques: polarimetric -- radio continnum: galaxies
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