Spectropolarimetry with the Allen Telescope Array: Revealing a New Dimension
Abstract
We present a novel analysis of the Faraday rotation properties of 37 bright, polarized radio sources. Observations with the Allen Telescope Array (ATA) cover frequencies from 1 to 2 GHz, which is sensitive to a range of Faraday rotation effects. We use RM synthesis to make the first detection of multiple RM components towards individual sources. Typically, these complexities in Faraday rotation have been treated as anomalies, but this technique reveals the true complexity of this process. Roughly a quarter of the sources studied have extra RM components with high confidence (brighter than ≈ 40 mJy), when observing with a RM resolution of roughly 100 rad m-2. We show that the peak RM cannot be determined more precisely than the RM beam size, but that the RMs from this work are consistent with that of earlier, narrow-bandwidth, all-sky surveys. This work also describes the polarimetry calibration procedure and that on-axis ATA observations of linear polarization can be calibrated to an accuracy of 0.2% of Stokes I. Future research directions include studying the time-dependent RM structure in Active Galactic Nuclei (AGNs) and enabling accurate, wide-area RM surveys to test models of Galactic and extragalactic magnetic fields.
- Publication:
-
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21724001L