A 189 MHz, 2400 deg<sup>2</sup> polarization survey with the murchison widefield array 32-element prototype

Bernardi, G; Greenhill, LJ; Mitchell, DA; Ord, SM; Hazelton, BJ; Gaensler, BM; De Oliveira-Costa, A; Morales, MF; Shankar, NU; Subrahmanyan, R; Wayth, RB; Lenc, E; Williams, CL; Arcus, W; Arora, BS; Barnes, DG; Bowman, JD; Briggs, FH; Bunton, JD; Cappallo, RJ; Corey, BE; Deshpande, A; deSouza, L; Emrich, D; Goeke, R; Herne, D; Hewitt, JN; Johnston-Hollitt, M; Kaplan, D; Kasper, JC; Kincaid, BB; Koenig, R; Kratzenberg, E; Lonsdale, CJ; Lynch, MJ; McWhirter, SR; Morgan, E; Oberoi, D; Pathikulangara, J; Prabu, T; Remillard, RA; Rogers, AEE; Roshi, A; Salah, JE; Sault, RJ; Srivani, KS; Stevens, J; Tingay, SJ; Waterson, M; Webster, RL; Whitney, AR; Williams, A; Wyithe, JSB

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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

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

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 ≥ 2^h30^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) = (4^h, –27 fdg

6) 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 sciences
Research Field:	Galactic astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Stevens, J (Dr Jamie Stevens)
ID Code:	88039
Year Published:	2013
Web of Science^® Times Cited:	80
Deposited By:	Mathematics and Physics
Deposited On:	2014-01-08
Last Modified:	2014-07-30
Downloads:	0

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