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...

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Main Authors:	Thyagarajan, N., Jacobs, D., Bowman, J., Barry, N., Beardsley, A., Bernardi, G., Briggs, F., Cappallo, R., Carroll, P., Corey, B., Oliveira-Costa, A., Dillon, J., Emrich, D., Ewall-Wice, A., Feng, L., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Hurley-Walker, N., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kim, H., Kittiwisit, P., Kratzenberg, E., Lenc, E., Line, J., Loeb, A., Lonsdale, C., Lynch, Mervyn, McKinley, B., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Neben, A., Oberoi, D., Offringa, A., Ord, Stephen, Paul, S., Pindor, B., Pober, J., Prabu, T., Procopio, P., Riding, J., Rogers, A., Roshi, A., Shankar, N., Sethi, S., Srivani, K., Subrahmanyan, R., Sullivan, I., Tegmark, M., Tingay, Steven, Trott, C., Waterson, M., Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C., Wu, C., Wyithe, J.
Format:	Journal Article
Published:	Institute of Physics Publishing 2015
Online Access:	http://hdl.handle.net/20.500.11937/9148

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author	Thyagarajan, N. Jacobs, D. Bowman, J. Barry, N. Beardsley, A. Bernardi, G. Briggs, F. Cappallo, R. Carroll, P. Corey, B. Oliveira-Costa, A. Dillon, J. Emrich, D. Ewall-Wice, A. Feng, L. Goeke, R. Greenhill, L. Hazelton, B. Hewitt, J. Hurley-Walker, N. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kim, H. Kittiwisit, P. Kratzenberg, E. Lenc, E. Line, J. Loeb, A. Lonsdale, C. Lynch, Mervyn McKinley, B. McWhirter, S. Mitchell, D. Morales, M. Morgan, E. Neben, A. Oberoi, D. Offringa, A. Ord, Stephen Paul, S. Pindor, B. Pober, J. Prabu, T. Procopio, P. Riding, J. Rogers, A. Roshi, A. Shankar, N. Sethi, S. Srivani, K. Subrahmanyan, R. Sullivan, I. Tegmark, M. Tingay, Steven Trott, C. Waterson, M. Wayth, Randall Webster, R. Whitney, A. Williams, A. Williams, C. Wu, C. Wyithe, J.
author_facet	Thyagarajan, N. Jacobs, D. Bowman, J. Barry, N. Beardsley, A. Bernardi, G. Briggs, F. Cappallo, R. Carroll, P. Corey, B. Oliveira-Costa, A. Dillon, J. Emrich, D. Ewall-Wice, A. Feng, L. Goeke, R. Greenhill, L. Hazelton, B. Hewitt, J. Hurley-Walker, N. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kim, H. Kittiwisit, P. Kratzenberg, E. Lenc, E. Line, J. Loeb, A. Lonsdale, C. Lynch, Mervyn McKinley, B. McWhirter, S. Mitchell, D. Morales, M. Morgan, E. Neben, A. Oberoi, D. Offringa, A. Ord, Stephen Paul, S. Pindor, B. Pober, J. Prabu, T. Procopio, P. Riding, J. Rogers, A. Roshi, A. Shankar, N. Sethi, S. Srivani, K. Subrahmanyan, R. Sullivan, I. Tegmark, M. Tingay, Steven Trott, C. Waterson, M. Wayth, Randall Webster, R. Whitney, A. Williams, A. Williams, C. Wu, C. Wyithe, J.
author_sort	Thyagarajan, N.
building	Curtin Institutional Repository
collection	Online Access
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	2025-11-14T06:24:10Z
format	Journal Article
id	curtin-20.500.11937-9148
institution	Curtin University Malaysia
institution_category	Local University
last_indexed	2025-11-14T06:24:10Z
publishDate	2015
publisher	Institute of Physics Publishing
recordtype	eprints
repository_type	Digital Repository
spelling	curtin-20.500.11937-91482023-02-22T06:24:16Z Foregrounds in wide-field Redshifted 21 cm power spectra Thyagarajan, N. Jacobs, D. Bowman, J. Barry, N. Beardsley, A. Bernardi, G. Briggs, F. Cappallo, R. Carroll, P. Corey, B. Oliveira-Costa, A. Dillon, J. Emrich, D. Ewall-Wice, A. Feng, L. Goeke, R. Greenhill, L. Hazelton, B. Hewitt, J. Hurley-Walker, N. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kim, H. Kittiwisit, P. Kratzenberg, E. Lenc, E. Line, J. Loeb, A. Lonsdale, C. Lynch, Mervyn McKinley, B. McWhirter, S. Mitchell, D. Morales, M. Morgan, E. Neben, A. Oberoi, D. Offringa, A. Ord, Stephen Paul, S. Pindor, B. Pober, J. Prabu, T. Procopio, P. Riding, J. Rogers, A. Roshi, A. Shankar, N. Sethi, S. Srivani, K. Subrahmanyan, R. Sullivan, I. Tegmark, M. Tingay, Steven Trott, C. Waterson, M. Wayth, Randall Webster, R. Whitney, A. Williams, A. Williams, C. Wu, C. Wyithe, J. 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. 2015 Journal Article http://hdl.handle.net/20.500.11937/9148 10.1088/0004-637X/804/1/14 Institute of Physics Publishing unknown
spellingShingle	Thyagarajan, N. Jacobs, D. Bowman, J. Barry, N. Beardsley, A. Bernardi, G. Briggs, F. Cappallo, R. Carroll, P. Corey, B. Oliveira-Costa, A. Dillon, J. Emrich, D. Ewall-Wice, A. Feng, L. Goeke, R. Greenhill, L. Hazelton, B. Hewitt, J. Hurley-Walker, N. Johnston-Hollitt, M. Kaplan, D. Kasper, J. Kim, H. Kittiwisit, P. Kratzenberg, E. Lenc, E. Line, J. Loeb, A. Lonsdale, C. Lynch, Mervyn McKinley, B. McWhirter, S. Mitchell, D. Morales, M. Morgan, E. Neben, A. Oberoi, D. Offringa, A. Ord, Stephen Paul, S. Pindor, B. Pober, J. Prabu, T. Procopio, P. Riding, J. Rogers, A. Roshi, A. Shankar, N. Sethi, S. Srivani, K. Subrahmanyan, R. Sullivan, I. Tegmark, M. Tingay, Steven Trott, C. Waterson, M. Wayth, Randall Webster, R. Whitney, A. Williams, A. Williams, C. Wu, C. Wyithe, J. 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/20.500.11937/9148

Foregrounds in wide-field Redshifted 21 cm power spectra

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