Abstract
We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg2. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam-1. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images, and deconvolution of the point-spread function through forward modeling. We present a point source catalog down to a flux limit of 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8% ± 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of 13 K, primarily with positive rotation measure values smaller than +10 rad m-2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at α ≥ 2h30 m where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at (α, δ) = (4h, -27.°6) in terms of three-dimensional power spectra.
Original language | English (US) |
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Article number | 105 |
Journal | Astrophysical Journal |
Volume | 771 |
Issue number | 2 |
DOIs | |
State | Published - 2013 |
Keywords
- ISM: magnetic fields
- diffuse radiation
- polarization
- radio continuum: general
- surveys
- techniques: interferometric
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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MWA Stokes I 189MHz sources
Bernardi, G. (Creator), Greenhill, L. J. (Creator), Mitchell, D. A. (Creator), Ord, S. M. (Creator), Hazelton, B. J. (Creator), Gaensler, B. M. (Creator), De Oliveira-Costa, O. A. (Creator), Morales, M. F. (Creator), Shankar, N. U. (Contributor), Subrahmanyan, R. (Creator), Wayth, R. B. (Creator), Lenc, E. (Creator), Williams, C. L. (Creator), Arcus, W. (Creator), Arora, B. S. (Creator), Barnes, D. G. (Creator), Bowman, J. (Creator), Briggs, F. H. (Creator), Bunton, J. D. (Creator), Cappallo, R. J. (Creator), Corey, B. E. (Creator), Deshpande, A. (Creator), Desouza, L. (Contributor), Emrich, D. (Creator), Goeke, R. (Creator), Herne, D. (Creator), Hewitt, J. N. (Creator), Johnston-Hollitt, M. (Creator), Kaplan, D. (Creator), Kasper, J. C. (Creator), Kincaid, B. B. (Creator), Koenig, R. (Creator), Kratzenberg, E. (Creator), Lonsdale, C. J. (Creator), Lynch, M. J. (Creator), McWhirter, S. R. (Creator), Morgan, E. (Creator), Oberoi, D. (Creator), Pathikulangara, J. (Creator), Prabu, T. (Creator), Remillard, R. A. (Creator), Rogers, A. E. E. (Contributor), Roshi, A. (Creator), Salah, J. E. (Creator), Sault, R. J. (Creator), Srivani, K. S. (Creator), Stevens, J. (Creator), Tingay, S. J. (Creator), Waterson, M. (Creator), Webster, R. L. (Creator), Whitney, A. R. (Creator), Williams, A. (Creator), Wyithe, J. S. B. (Contributor), Bernardi, G. (Creator), Greenhill, L. J. (Creator), Gaensler, B. M. (Creator), Morales, M. F. (Creator), Kaplan, D. (Creator), Lonsdale, C. J. (Creator), Sault, R. J. (Creator), Tingay, S. J. (Creator), Webster, R. L. (Creator) & Wyithe, J. S. B. (Contributor), Centre de Donnees Strasbourg (CDS), 2015
DOI: 10.26093/cds/vizier.17710105, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/771/105
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