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CYBERSKA
A Cyberinfrastructure platform to meet the needs of data intensive radio astronomy on route to the SKA |
Radio Polarimetry of the ELAIS N1 Field: Polarized Compact Sources
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Year: 2007
Volume: 666
Pages: 201 - 211
Abstract:
We present deep polarimetric observations at 1420 MHz of the European Large Area ISO Survey North 1 region (ELAIS N1) as part of the Dominion Radio Astrophysical Observatory Planck Deep Fields project. By combining closely spaced aperture synthesis fields, we image a region of 7.43 deg2 to a maximum sensitivity in Stokes Q and U of 78 μJy beam-1, and detect 786 compact sources in Stokes I. Of these, 83 exhibit polarized emission. We find that the differential source counts (logN-logp) for polarized sources are nearly constant down to p>500 μJy, and that these faint polarized radio sources are more highly polarized than the strong source population. The median fractional polarization is 4.8%+/-0.7% for polarized sources with Stokes I flux density between 10 and 30 mJy, approximately 3 times larger than sources with I>100 mJy. The majority of the polarized sources have been identified with galaxies in the Spitzer Wide Area Infrared Extragalactic Survey (SWIRE) image of ELAIS N1. Most of the galaxies occupy regions in the IRAC 5.8 μm/3.6 μm versus 8.0 μm/4.5 μm color-color diagram associated with dusty AGNs, or with ellipticals with an aging stellar population. A few host galaxies have colors that suggests significant PAH emission in the near-infrared. A small fraction, 12%, of the polarized sources are not detected in the SWIRE data. None of the polarized sources in our sample appears to be associated with an actively star-forming galaxy.
