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Paper: High-Resolution Spectro-Polarimetric Radio Surveys
Volume: 407, The Low-Frequency Radio Universe
Page: 12
Authors: Taylor, A.R.
Abstract: Spectro-polarimetric data at radio wavelengths provide a probe of cosmic magnetic fields both within our Galaxy and the extragalactic Universe. Wide-field interferometric observations are beginning to make significant advances in our understanding of cosmic magnetism. The DRAO Synthesis Telescope in Penticton Canada has been used to carry out arcminute-resolution deep surveys of the polarized emission from extragalactic sources at 1.4 GHz at high latitude, achieving a sensitivity of 45 μJy. These data show an increase in the average fractional polarization of AGN integrated radio emission down to the sub-mJy regime. This trend can be explained only partially via models that include a luminosity dependence of polarization for FR I radio galaxies. The deep polarization sky thus presents a puzzle that cannot be understood by simple extrapolations of properties of the strong AGN source population. We have also re-analysed the visibility data from the NRAO VLA Sky Survey (NVSS) to create a RM image of the sky from over thirty-seven thousand RM values covering the region north of δ = −40°. The resolution and sensitivity of these data allow background radio sources to be used as probes of the Faraday rotation from the magneto-ionic medium of the Milky Way and the structure of the Galactic magnetic field. The results of these large-area and deep polarimetric observations point the way for new polarization surveys such as GALFACTS and planned surveys with the GMRT and SKA pathfinders.
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