FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA
Detection of 21 cm emission of H i from the epoch of reionization, at redshifts z > 6, is limited primarily by foreground emission. We investigate the signatures of wide-field measurements and an all-sky foreground model using the delay spectrum technique that maps the measurements to foreground...
| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/97096 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-1941-7458 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 |
| _version_ | 1826202823708114944 |
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| author | Cappallo, Roger J. Corey, Brian E. de Oliveira-Costa, Angelica Dillon, Joshua Shane Ewall-Wice, Aaron Michael Feng, L. Goeke, Robert F. Hewitt, Jacqueline N. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Neben, Abraham Richard Rogers, Alan E. E. Tegmark, Max Erik Whitney, Alan R. Williams, Christopher Leigh |
| author2 | Haystack Observatory |
| author_facet | Haystack Observatory Cappallo, Roger J. Corey, Brian E. de Oliveira-Costa, Angelica Dillon, Joshua Shane Ewall-Wice, Aaron Michael Feng, L. Goeke, Robert F. Hewitt, Jacqueline N. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Neben, Abraham Richard Rogers, Alan E. E. Tegmark, Max Erik Whitney, Alan R. Williams, Christopher Leigh |
| author_sort | Cappallo, Roger J. |
| collection | MIT |
| description | Detection of 21 cm emission of H i from the epoch of reionization, at redshifts z > 6, is limited primarily by foreground emission. We investigate the signatures of wide-field measurements and an all-sky foreground model using the delay spectrum technique that maps the measurements to foreground object locations through signal delays between antenna pairs. We demonstrate interferometric measurements are inherently sensitive to all scales, including the largest angular scales, owing to the nature of wide-field measurements. These wide-field effects are generic to all observations but antenna shapes impact their amplitudes substantially. A dish-shaped antenna yields the most desirable features from a foreground contamination viewpoint, relative to a dipole or a phased array. Comparing data from recent Murchison Widefield Array observations, we demonstrate that the foreground signatures that have the largest impact on the H i signal arise from power received far away from the primary field of view. We identify diffuse emission near the horizon as a significant contributing factor, even on wide antenna spacings that usually represent structures on small scales. For signals entering through the primary field of view, compact emission dominates the foreground contamination. These two mechanisms imprint a characteristic pitchfork signature on the "foreground wedge" in Fourier delay space. Based on these results, we propose that selective down-weighting of data based on antenna spacing and time can mitigate foreground contamination substantially by a factor of ~100 with negligible loss of sensitivity. |
| first_indexed | 2024-09-23T12:20:18Z |
| format | Article |
| id | mit-1721.1/97096 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:20:18Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/970962022-09-28T01:03:13Z FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA Cappallo, Roger J. Corey, Brian E. de Oliveira-Costa, Angelica Dillon, Joshua Shane Ewall-Wice, Aaron Michael Feng, L. Goeke, Robert F. Hewitt, Jacqueline N. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Neben, Abraham Richard Rogers, Alan E. E. Tegmark, Max Erik Whitney, Alan R. Williams, Christopher Leigh Haystack Observatory Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Cappallo, Roger J. Corey, Brian E. de Oliveira-Costa, Angelica Dillon, Joshua Shane Ewall-Wice, Aaron Michael Feng, L. Goeke, Robert F. Hewitt, Jacqueline N. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Neben, Abraham Richard Rogers, Alan E. E. Tegmark, Max Erik Whitney, Alan R. Williams, Christopher Leigh Detection of 21 cm emission of H i from the epoch of reionization, at redshifts z > 6, is limited primarily by foreground emission. We investigate the signatures of wide-field measurements and an all-sky foreground model using the delay spectrum technique that maps the measurements to foreground object locations through signal delays between antenna pairs. We demonstrate interferometric measurements are inherently sensitive to all scales, including the largest angular scales, owing to the nature of wide-field measurements. These wide-field effects are generic to all observations but antenna shapes impact their amplitudes substantially. A dish-shaped antenna yields the most desirable features from a foreground contamination viewpoint, relative to a dipole or a phased array. Comparing data from recent Murchison Widefield Array observations, we demonstrate that the foreground signatures that have the largest impact on the H i signal arise from power received far away from the primary field of view. We identify diffuse emission near the horizon as a significant contributing factor, even on wide antenna spacings that usually represent structures on small scales. For signals entering through the primary field of view, compact emission dominates the foreground contamination. These two mechanisms imprint a characteristic pitchfork signature on the "foreground wedge" in Fourier delay space. Based on these results, we propose that selective down-weighting of data based on antenna spacing and time can mitigate foreground contamination substantially by a factor of ~100 with negligible loss of sensitivity. National Science Foundation (U.S.) (Award AST-1109257) 2015-05-28T17:43:35Z 2015-05-28T17:43:35Z 2015-04 2014-11 Article http://purl.org/eprint/type/JournalArticle 1538-4357 http://hdl.handle.net/1721.1/97096 Thyagarajan, Nithyanandan, Daniel C. Jacobs, Judd D. Bowman, N. Barry, A. P. Beardsley, G. Bernardi, F. Briggs, et al. “FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 Cm POWER SPECTRA.” The Astrophysical Journal 804, no. 1 (April 24, 2015): 14. © 2015 The American Astronomical Society https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-1941-7458 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 en_US http://dx.doi.org/10.1088/0004-637X/804/1/14 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 IOP Publishing |
| spellingShingle | Cappallo, Roger J. Corey, Brian E. de Oliveira-Costa, Angelica Dillon, Joshua Shane Ewall-Wice, Aaron Michael Feng, L. Goeke, Robert F. Hewitt, Jacqueline N. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Neben, Abraham Richard Rogers, Alan E. E. Tegmark, Max Erik Whitney, Alan R. Williams, Christopher Leigh FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title | FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title_full | FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title_fullStr | FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title_full_unstemmed | FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title_short | FOREGROUNDS IN WIDE-FIELD REDSHIFTED 21 cm POWER SPECTRA |
| title_sort | foregrounds in wide field redshifted 21 cm power spectra |
| url | http://hdl.handle.net/1721.1/97096 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7776-7240 https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0002-0086-7363 https://orcid.org/0000-0003-1941-7458 https://orcid.org/0000-0003-3336-9958 https://orcid.org/0000-0001-7670-7190 https://orcid.org/0000-0003-0422-2324 |
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