DRAO deep polarization study at 1.4 GHz

The Dominion Radio Astrophysical Observatory synthesis telescope (DRAO-ST) was used to produce a deep polarization mosaic at 1.4 GHz to a noise level of 45 microJy beam⁻¹ for both Stokes Q and U at 1' resolution. The DRAO deep field covers 8.6 sq. degrees in polarization centered on the ELAIS N1 field. We identified over 1700 total intensity (Stokes I) radio sources of which 197 are linearly polarized down to a flux density level of 203 microJy. The fractional polarization of faint polarized sources are flat down to a polarized flux density of about 4 mJy, at which point the numbers increase, until the counts drop for polarized flux densities below 1 mJy. These faint polarized radio sources are mostly AGNs with luminosities below the traditional FRI/FRII boundary. Follow-up observations with the VLA show that the origin of the polarization of the radio sources down to a polarized flux of 1 mJy comes from both the lobes and central region of these objects.