A 189 MHz, 2400 deg2 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 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...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Journal Article |
| Published: |
Institute of Physics Publishing, Inc.
2013
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/20.500.11937/32095 |
| _version_ | 1848753566753226752 |
|---|---|
| author | Bernardi, G . Greenhill, L. Mitchell, D. Ord, S. Hazelton, B. Gaensler, B. de Oliveira-Costa, A. Morales, M. Udaya Shankar, N. Subrahmanyan, R. Wayth, Randall Lenc, E. Williams, C. Arcus, Wayne Arora, B. Barnes, D. Bowman, J. Briggs, F. Bunton, J. Cappallo, R. Corey, B. Deshpande, A. deSouza, L. Emrich, David Goeke, R. Herne, D. Hewitt, J. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kincaid, B. Koenig, R. Kratzenberg, E. Lonsdale, C. Lynch, Mervyn McWhirter, S. Morgan, E. Oberoi, D. Pathikulangara, J. Prabu, T. Remillard, R. Rogers, A. Roshi, A. Salah, J. Sault, R. Srivani, K. Tingay, Steven Waterson, Mark Webster, R. Whitney, A. Williams, A. Wyithe, J. |
| author_facet | Bernardi, G . Greenhill, L. Mitchell, D. Ord, S. Hazelton, B. Gaensler, B. de Oliveira-Costa, A. Morales, M. Udaya Shankar, N. Subrahmanyan, R. Wayth, Randall Lenc, E. Williams, C. Arcus, Wayne Arora, B. Barnes, D. Bowman, J. Briggs, F. Bunton, J. Cappallo, R. Corey, B. Deshpande, A. deSouza, L. Emrich, David Goeke, R. Herne, D. Hewitt, J. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kincaid, B. Koenig, R. Kratzenberg, E. Lonsdale, C. Lynch, Mervyn McWhirter, S. Morgan, E. Oberoi, D. Pathikulangara, J. Prabu, T. Remillard, R. Rogers, A. Roshi, A. Salah, J. Sault, R. Srivani, K. Tingay, Steven Waterson, Mark Webster, R. Whitney, A. Williams, A. Wyithe, J. |
| author_sort | Bernardi, G . |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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 >= 2h30m 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. |
| first_indexed | 2025-11-14T08:26:33Z |
| format | Journal Article |
| id | curtin-20.500.11937-32095 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:26:33Z |
| publishDate | 2013 |
| publisher | Institute of Physics Publishing, Inc. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-320952017-09-13T15:36:22Z A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype Bernardi, G . Greenhill, L. Mitchell, D. Ord, S. Hazelton, B. Gaensler, B. de Oliveira-Costa, A. Morales, M. Udaya Shankar, N. Subrahmanyan, R. Wayth, Randall Lenc, E. Williams, C. Arcus, Wayne Arora, B. Barnes, D. Bowman, J. Briggs, F. Bunton, J. Cappallo, R. Corey, B. Deshpande, A. deSouza, L. Emrich, David Goeke, R. Herne, D. Hewitt, J. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kincaid, B. Koenig, R. Kratzenberg, E. Lonsdale, C. Lynch, Mervyn McWhirter, S. Morgan, E. Oberoi, D. Pathikulangara, J. Prabu, T. Remillard, R. Rogers, A. Roshi, A. Salah, J. Sault, R. Srivani, K. Tingay, Steven Waterson, Mark Webster, R. Whitney, A. Williams, A. Wyithe, J. radio continuum: general polarization ISM: magnetic fields surveys diffuse radiation techniques: interferometric 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 >= 2h30m 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. 2013 Journal Article http://hdl.handle.net/20.500.11937/32095 10.1088/0004-637X/771/2/105 Institute of Physics Publishing, Inc. fulltext |
| spellingShingle | radio continuum: general polarization ISM: magnetic fields surveys diffuse radiation techniques: interferometric Bernardi, G . Greenhill, L. Mitchell, D. Ord, S. Hazelton, B. Gaensler, B. de Oliveira-Costa, A. Morales, M. Udaya Shankar, N. Subrahmanyan, R. Wayth, Randall Lenc, E. Williams, C. Arcus, Wayne Arora, B. Barnes, D. Bowman, J. Briggs, F. Bunton, J. Cappallo, R. Corey, B. Deshpande, A. deSouza, L. Emrich, David Goeke, R. Herne, D. Hewitt, J. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kincaid, B. Koenig, R. Kratzenberg, E. Lonsdale, C. Lynch, Mervyn McWhirter, S. Morgan, E. Oberoi, D. Pathikulangara, J. Prabu, T. Remillard, R. Rogers, A. Roshi, A. Salah, J. Sault, R. Srivani, K. Tingay, Steven Waterson, Mark Webster, R. Whitney, A. Williams, A. Wyithe, J. A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title | A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title_full | A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title_fullStr | A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title_full_unstemmed | A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title_short | A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype |
| title_sort | 189 mhz, 2400 deg2 polarization survey with the murchison widefield array 32-element prototype |
| topic | radio continuum: general polarization ISM: magnetic fields surveys diffuse radiation techniques: interferometric |
| url | http://hdl.handle.net/20.500.11937/32095 |