A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE
We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg[superscript 2]. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam[superscript –1]. We demonstrate a novel interferometric data analysis t...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/94548 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 |
| _version_ | 1811092546589294592 |
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| author | Williams, Christopher Leigh Goeke, Robert F. Hewitt, Jacqueline N. Morgan, Edward H. Remillard, Ronald Alan Cappallo, Roger J. Corey, Brian E. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. |
| author2 | Haystack Observatory |
| author_facet | Haystack Observatory Williams, Christopher Leigh Goeke, Robert F. Hewitt, Jacqueline N. Morgan, Edward H. Remillard, Ronald Alan Cappallo, Roger J. Corey, Brian E. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. |
| author_sort | Williams, Christopher Leigh |
| collection | MIT |
| description | We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg[superscript 2]. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam[superscript –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[superscript –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[superscript h]30[superscript 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[superscript h], –27[° over .]6) in terms of three-dimensional power spectra. |
| first_indexed | 2024-09-23T15:19:56Z |
| format | Article |
| id | mit-1721.1/94548 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T15:19:56Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/945482022-10-02T02:13:32Z A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE Williams, Christopher Leigh Goeke, Robert F. Hewitt, Jacqueline N. Morgan, Edward H. Remillard, Ronald Alan Cappallo, Roger J. Corey, Brian E. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Haystack Observatory MIT Kavli Institute for Astrophysics and Space Research Williams, Christopher Leigh Goeke, Robert F. Hewitt, Jacqueline N. Morgan, Edward H. Remillard, Ronald Alan Cappallo, Roger J. Corey, Brian E. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg[superscript 2]. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam[superscript –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[superscript –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[superscript h]30[superscript 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[superscript h], –27[° over .]6) in terms of three-dimensional power spectra. Australian Research Council (Grant LE0775621) Australian Research Council (Grant LE0882938) National Science Foundation (U.S.) (Grant AST-0457585) National Science Foundation (U.S.) (Grant AST-0821321) National Science Foundation (U.S.) (Grant AST-0908884) National Science Foundation (U.S.) (Grant AST-1008353) National Science Foundation (U.S.) (Grant PHY-0835713) United States. Air Force Office of Scientific Research (Grant FA9550-0510247) 2015-02-17T15:14:38Z 2015-02-17T15:14:38Z 2013-06 2012-08 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/94548 Bernardi, G., L. J. Greenhill, D. A. Mitchell, S. M. Ord, B. J. Hazelton, B. M. Gaensler, A. de Oliveira-Costa, et al. “A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE.” The Astrophysical Journal 771, no. 2 (June 24, 2013): 105. © 2013 The American Astronomical Society https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 en_US http://dx.doi.org/10.1088/0004-637X/771/2/105 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Williams, Christopher Leigh Goeke, Robert F. Hewitt, Jacqueline N. Morgan, Edward H. Remillard, Ronald Alan Cappallo, Roger J. Corey, Brian E. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title | A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title_full | A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title_fullStr | A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title_full_unstemmed | A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title_short | A 189 MHz, 2400 Deg[superscript 2] POLARIZATION SURVEY WITH THE MURCHISON WIDEFIELD ARRAY 32-ELEMENT PROTOTYPE |
| title_sort | 189 mhz 2400 deg superscript 2 polarization survey with the murchison widefield array 32 element prototype |
| url | http://hdl.handle.net/1721.1/94548 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 |
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