Journal article
Complex Faraday depth structure of active galactic nuclei as revealed by broad-band radio polarimetry
Monthly notices of the Royal Astronomical Society, Vol.421(4), pp.3300-3315
04/2012
DOI: 10.1111/j.1365-2966.2012.20554.x
Abstract
We present a detailed study of the Faraday depth structure of four bright (>1 Jy), strongly polarized, unresolved radio-loud quasars. The Australia Telescope Compact Array (ATCA) was used to observe these sources with 2 GHz of instantaneous bandwidth from 1.1 to 3.1 GHz. This allowed us to spectrally resolve the polarization structure of spatially unresolved radio sources, and by fitting various Faraday rotation models to the data, we conclusively demonstrate that two of the sources cannot be described by a simple rotation measure (RM) component modified by depolarization from a foreground Faraday screen. Our results have important implications for using background extragalactic radio sources as probes of the Galactic and intergalactic magneto-ionic media as we show how RM estimations from narrow-bandwidth observations can give erroneous results in the presence of multiple interfering Faraday components. We postulate that the additional RM components arise from polarized structure in the compact inner regions of the radio source itself and not from polarized emission from galactic or intergalactic foreground regions. We further suggest that this may contribute significantly to any RM time variability seen in RM studies on these angular scales. Follow-up, high-sensitivity very long baseline interferometry (VLBI) observations of these sources will directly test our predictions.
Details
- Title: Subtitle
- Complex Faraday depth structure of active galactic nuclei as revealed by broad-band radio polarimetry
- Creators
- S. P. O'Sullivan - CSIRO Astron & Space Sci, ATNF, Epping, NSW 1710, AustraliaS. Brown - Astronomy and SpaceT. Robishaw - Herzberg Institute of AstrophysicsD. H. F. M. Schnitzeler - CSIRO Astron & Space Sci, ATNF, Epping, NSW 1710, AustraliaN. M. McClure-Griffiths - Astronomy and SpaceI. J. Feain - Commonwealth Scientific and Industrial Research OrganisationA. R. Taylor - University of CalgaryB. M. Gaensler - University of SydneyT. L. Landecker - Herzberg Institute of AstrophysicsL. Harvey-Smith - Astronomy and SpaceE. Carretti - Commonwealth Scientific and Industrial Research Organisation
- Resource Type
- Journal article
- Publication Details
- Monthly notices of the Royal Astronomical Society, Vol.421(4), pp.3300-3315
- Publisher
- Oxford Univ Press
- DOI
- 10.1111/j.1365-2966.2012.20554.x
- ISSN
- 0035-8711
- eISSN
- 1365-2966
- Number of pages
- 16
- Grant note
- DP0986386; FS100100033 / Australian Research Council Commonwealth of Australia; Australian Government National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA)
- Language
- English
- Date published
- 04/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429010802771
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