Issue |
A&A
Volume 415, Number 2, February IV 2004
|
|
---|---|---|
Page(s) | 549 - 558 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20034632 | |
Published online | 11 February 2004 |
High-frequency polarization properties of southern Kühr sources
1
SISSA/ISAS, Via Beirut 2–4, 34014 Trieste, Italy
2
Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 2121, Australia
3
Istituto di Radioastronomia, CNR, Via Gobetti 101, 40129, Bologna, Italy
4
INAF, Osservatorio Astronomico di Bologna, Via Ranzani 1, 40126 Bologna, Italy
5
INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy e-mail: dezotti@pd.astro.it
Corresponding author: R. Ricci, ricci@sissa.it
Received:
5
August
2003
Accepted:
21
November
2003
We have observed 250 of the 258 southern sources in the
complete 5 GHz 1 Jy sample by Kühr et al. ([CITE])
using the Australia Telescope Compact Array (ATCA) at 18.5 GHz.
This paper focuses on the polarization properties of this sample,
while other properties
will be addressed in a future paper.
The analysis subdivides the sample into flat and steep spectrum
sources using the classification of Stickel et al. ([CITE]),
where spectral indices were measured between 2.7 and 5 GHz.
The polarized flux has been measured with a for 170
sources (114 flat-spectrum and 56 steep-spectrum). Upper
limits have been set for additional 27 sources (12 flat-spectrum and 15
steep-spectrum). The median fractional
polarization at 18.5 GHz for the flat-spectrum
sub-sample is
, which is
about a factor of 2 higher than at 1.4
GHz (
, based on NVSS data).
No evidence was found
of significant correlations of the fractional polarization with other source
properties. The median value of
for the
steep spectrum sources is
4.8%, but our
sample might be biased against extended sources.
We find some correlation between
and both
the low-frequency (1.4–5 GHz) and the high-frequency
(5–18.5 GHz) spectral indices.
An important application of this work is in estimating
the contamination of CMB polarization maps by extragalactic radio sources.
Our results indicate that such contamination
is within that estimated by Mesa et al. ([CITE]).
Key words: radio continuum: galaxies / galaxies: nuclei / quasars: general / BL Lacertae objects: general / surveys
© ESO, 2004
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