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A 189 MHz, 2400 deg2 polarization survey with the murchison widefield array 32-element prototype

Citation

Bernardi, G and Greenhill, LJ and Mitchell, DA and Ord, SM and Hazelton, BJ and Gaensler, BM and De Oliveira-Costa, A and Morales, MF and Shankar, NU and Subrahmanyan, R and Wayth, RB and Lenc, E and Williams, CL and Arcus, W and Arora, BS and Barnes, DG and Bowman, JD and Briggs, FH and Bunton, JD and Cappallo, RJ and Corey, BE and Deshpande, A and deSouza, L and Emrich, D and Goeke, R and Herne, D and Hewitt, JN and Johnston-Hollitt, M and Kaplan, D and Kasper, JC and Kincaid, BB and Koenig, R and Kratzenberg, E and Lonsdale, CJ and Lynch, MJ and McWhirter, SR and Morgan, E and Oberoi, D and Pathikulangara, J and Prabu, T and Remillard, RA and Rogers, AEE and Roshi, A and Salah, JE and Sault, RJ and Srivani, KS and Stevens, J and Tingay, SJ and Waterson, M and Webster, RL and Whitney, AR and Williams, A and Wyithe, JSB, A 189 MHz, 2400 deg2 polarization survey with the murchison widefield array 32-element prototype, Astrophysical Journal, 771, (2) Article 105. ISSN 0004-637X (2013) [Refereed Article]

Copyright Statement

Copyright 2013 The American Astronomical Society

DOI: doi:10.1088/0004-637X/771/2/105

Abstract

We present a Stokes I, Q and U survey at 189MHz with the Murchison Widefield Array 32 element prototype covering 2400deg2. The survey has a 15.6arcmin angular resolution and achieves a noise level of 15mJybeam1. 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 4Jy. 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 1.4GHz, 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 +10radm2. 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 ≥ 2h30m where the diffuse polarized emission rms is fainter than 1K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at (α, δ) = (4h, 27fdg6) in terms of three-dimensional power spectra

Item Details

Item Type:Refereed Article
Keywords:diffuse radiation ISM: magnetic fields polarization radio continuum: general surveys techniques: interferometric
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Stevens, J (Dr Jamie Stevens)
ID Code:88039
Year Published:2013
Web of Science® Times Cited:37
Deposited By:Mathematics and Physics
Deposited On:2014-01-08
Last Modified:2014-07-30
Downloads:0

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