THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS

J. C. Pober; B. J. Hazelton; A. P. Beardsley; N. A. Barry; Z. E. Martinot; I. S. Sullivan; M. F. Morales; M. E. Bell; G. Bernardi; N. D R Bhat; Judd Bowman; F. Briggs; R. J. Cappallo; P. Carroll; B. E. Corey; A. De Oliveira-Costa; A. A. Deshpande; Joshua S. Dillon; D. Emrich; A. M. Ewall-Wice; L. Feng; R. Goeke; L. J. Greenhill; J. N. Hewitt; L. Hindson; N. Hurley-Walker; Daniel Jacobs; M. Johnston-Hollitt; D. L. Kaplan; J. C. Kasper; Han Seek Kim; P. Kittiwisit; E. Kratzenberg; N. Kudryavtseva; E. Lenc; J. Line; A. Loeb; C. J. Lonsdale; M. J. Lynch; B. McKinley; S. R. McWhirter; D. A. Mitchell; E. Morgan; A. R. Neben; D. Oberoi; A. R. Offringa; S. M. Ord; Sourabh Paul; B. Pindor; T. Prabu; P. Procopio; J. Riding; A. E E Rogers; A. Roshi; Shiv K. Sethi; N. Udaya Shankar; K. S. Srivani; R. Subrahmanyan; M. Tegmark; Nithyanandan Thyagarajan; S. J. Tingay; C. M. Trott; M. Waterson; R. B. Wayth; R. L. Webster; A. R. Whitney; A. Williams; C. L. Williams; J. S B Wyithe

doi:10.3847/0004-637X/819/1/8

THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS

J. C. Pober, B. J. Hazelton, A. P. Beardsley, N. A. Barry, Z. E. Martinot, I. S. Sullivan, M. F. Morales, M. E. Bell, G. Bernardi, N. D R Bhat, Judd Bowman, F. Briggs, R. J. Cappallo, P. Carroll, B. E. Corey, A. De Oliveira-Costa, A. A. Deshpande, Joshua S. Dillon, D. Emrich, A. M. Ewall-WiceL. Feng, R. Goeke, L. J. Greenhill, J. N. Hewitt, L. Hindson, N. Hurley-Walker, Daniel Jacobs, M. Johnston-Hollitt, D. L. Kaplan, J. C. Kasper, Han Seek Kim, P. Kittiwisit, E. Kratzenberg, N. Kudryavtseva, E. Lenc, J. Line, A. Loeb, C. J. Lonsdale, M. J. Lynch, B. McKinley, S. R. McWhirter, D. A. Mitchell, E. Morgan, A. R. Neben, D. Oberoi, A. R. Offringa, S. M. Ord, Sourabh Paul, B. Pindor, T. Prabu, P. Procopio, J. Riding, A. E E Rogers, A. Roshi, Shiv K. Sethi, N. Udaya Shankar, K. S. Srivani, R. Subrahmanyan, M. Tegmark, Nithyanandan Thyagarajan, S. J. Tingay, C. M. Trott, M. Waterson, R. B. Wayth, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, J. S B Wyithe

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

68 Scopus citations

Abstract

In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model that includes sources in both the main field of view and the first sidelobes reduces the contamination in high k_∥ modes by several per cent relative to a model that only includes sources in the main field of view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any Epoch of Reionization signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the instrument's main field of view to potentially recover the full 21 cm power spectrum.

Original language	English (US)
Article number	8
Journal	Astrophysical Journal
Volume	819
Issue number	1
DOIs	https://doi.org/10.3847/0004-637X/819/1/8
State	Published - Mar 1 2016

Keywords

cosmology: observations
dark ages, reionization, first stars
techniques: interferometric

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/0004-637X/819/1/8

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Pober, J. C., Hazelton, B. J., Beardsley, A. P., Barry, N. A., Martinot, Z. E., Sullivan, I. S., Morales, M. F., Bell, M. E., Bernardi, G., Bhat, N. D. R., Bowman, J., Briggs, F., Cappallo, R. J., Carroll, P., Corey, B. E., De Oliveira-Costa, A., Deshpande, A. A., Dillon, J. S., Emrich, D., ... Wyithe, J. S. B. (2016). THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS. Astrophysical Journal, 819(1), Article 8. https://doi.org/10.3847/0004-637X/819/1/8

Pober, JC, Hazelton, BJ, Beardsley, AP, Barry, NA, Martinot, ZE, Sullivan, IS, Morales, MF, Bell, ME, Bernardi, G, Bhat, NDR, Bowman, J, Briggs, F, Cappallo, RJ, Carroll, P, Corey, BE, De Oliveira-Costa, A, Deshpande, AA, Dillon, JS, Emrich, D, Ewall-Wice, AM, Feng, L, Goeke, R, Greenhill, LJ, Hewitt, JN, Hindson, L, Hurley-Walker, N, Jacobs, D, Johnston-Hollitt, M, Kaplan, DL, Kasper, JC, Kim, HS, Kittiwisit, P, Kratzenberg, E, Kudryavtseva, N, Lenc, E, Line, J, Loeb, A, Lonsdale, CJ, Lynch, MJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morgan, E, Neben, AR, Oberoi, D, Offringa, AR, Ord, SM, Paul, S, Pindor, B, Prabu, T, Procopio, P, Riding, J, Rogers, AEE, Roshi, A, Sethi, SK, Shankar, NU, Srivani, KS, Subrahmanyan, R, Tegmark, M, Thyagarajan, N, Tingay, SJ, Trott, CM, Waterson, M, Wayth, RB, Webster, RL, Whitney, AR, Williams, A, Williams, CL & Wyithe, JSB 2016, 'THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS', Astrophysical Journal, vol. 819, no. 1, 8. https://doi.org/10.3847/0004-637X/819/1/8

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title = "THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS",

abstract = "In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model that includes sources in both the main field of view and the first sidelobes reduces the contamination in high k∥ modes by several per cent relative to a model that only includes sources in the main field of view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any Epoch of Reionization signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the instrument's main field of view to potentially recover the full 21 cm power spectrum.",

keywords = "cosmology: observations, dark ages, reionization, first stars, techniques: interferometric",

author = "Pober, {J. C.} and Hazelton, {B. J.} and Beardsley, {A. P.} and Barry, {N. A.} and Martinot, {Z. E.} and Sullivan, {I. S.} and Morales, {M. F.} and Bell, {M. E.} and G. Bernardi and Bhat, {N. D R} and Judd Bowman and F. Briggs and Cappallo, {R. J.} and P. Carroll and Corey, {B. E.} and {De Oliveira-Costa}, A. and Deshpande, {A. A.} and Dillon, {Joshua S.} and D. Emrich and Ewall-Wice, {A. M.} and L. Feng and R. Goeke and Greenhill, {L. J.} and Hewitt, {J. N.} and L. Hindson and N. Hurley-Walker and Daniel Jacobs and M. Johnston-Hollitt and Kaplan, {D. L.} and Kasper, {J. C.} and Kim, {Han Seek} and P. Kittiwisit and E. Kratzenberg and N. Kudryavtseva and E. Lenc and J. Line and A. Loeb and Lonsdale, {C. J.} and Lynch, {M. J.} and B. McKinley and McWhirter, {S. R.} and Mitchell, {D. A.} and E. Morgan and Neben, {A. R.} and D. Oberoi and Offringa, {A. R.} and Ord, {S. M.} and Sourabh Paul and B. Pindor and T. Prabu and P. Procopio and J. Riding and Rogers, {A. E E} and A. Roshi and Sethi, {Shiv K.} and Shankar, {N. Udaya} and Srivani, {K. S.} and R. Subrahmanyan and M. Tegmark and Nithyanandan Thyagarajan and Tingay, {S. J.} and Trott, {C. M.} and M. Waterson and Wayth, {R. B.} and Webster, {R. L.} and Whitney, {A. R.} and A. Williams and Williams, {C. L.} and Wyithe, {J. S B}",

year = "2016",

month = mar,

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doi = "10.3847/0004-637X/819/1/8",

language = "English (US)",

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journal = "Astrophysical Journal",

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TY - JOUR

T1 - THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY

T2 - A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS

AU - Pober, J. C.

AU - Hazelton, B. J.

AU - Beardsley, A. P.

AU - Barry, N. A.

AU - Martinot, Z. E.

AU - Sullivan, I. S.

AU - Morales, M. F.

AU - Bell, M. E.

AU - Bernardi, G.

AU - Bhat, N. D R

AU - Bowman, Judd

AU - Briggs, F.

AU - Cappallo, R. J.

AU - Carroll, P.

AU - Corey, B. E.

AU - De Oliveira-Costa, A.

AU - Deshpande, A. A.

AU - Dillon, Joshua S.

AU - Emrich, D.

AU - Ewall-Wice, A. M.

AU - Feng, L.

AU - Goeke, R.

AU - Greenhill, L. J.

AU - Hewitt, J. N.

AU - Hindson, L.

AU - Hurley-Walker, N.

AU - Jacobs, Daniel

AU - Johnston-Hollitt, M.

AU - Kaplan, D. L.

AU - Kasper, J. C.

AU - Kim, Han Seek

AU - Kittiwisit, P.

AU - Kratzenberg, E.

AU - Kudryavtseva, N.

AU - Lenc, E.

AU - Line, J.

AU - Loeb, A.

AU - Lonsdale, C. J.

AU - Lynch, M. J.

AU - McKinley, B.

AU - McWhirter, S. R.

AU - Mitchell, D. A.

AU - Morgan, E.

AU - Neben, A. R.

AU - Oberoi, D.

AU - Offringa, A. R.

AU - Ord, S. M.

AU - Paul, Sourabh

AU - Pindor, B.

AU - Prabu, T.

AU - Procopio, P.

AU - Riding, J.

AU - Rogers, A. E E

AU - Roshi, A.

AU - Sethi, Shiv K.

AU - Shankar, N. Udaya

AU - Srivani, K. S.

AU - Subrahmanyan, R.

AU - Tegmark, M.

AU - Thyagarajan, Nithyanandan

AU - Tingay, S. J.

AU - Trott, C. M.

AU - Waterson, M.

AU - Wayth, R. B.

AU - Webster, R. L.

AU - Whitney, A. R.

AU - Williams, A.

AU - Williams, C. L.

AU - Wyithe, J. S B

PY - 2016/3/1

Y1 - 2016/3/1

N2 - In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model that includes sources in both the main field of view and the first sidelobes reduces the contamination in high k∥ modes by several per cent relative to a model that only includes sources in the main field of view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any Epoch of Reionization signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the instrument's main field of view to potentially recover the full 21 cm power spectrum.

AB - In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model that includes sources in both the main field of view and the first sidelobes reduces the contamination in high k∥ modes by several per cent relative to a model that only includes sources in the main field of view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any Epoch of Reionization signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the instrument's main field of view to potentially recover the full 21 cm power spectrum.

KW - cosmology: observations

KW - dark ages, reionization, first stars

KW - techniques: interferometric

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DO - 10.3847/0004-637X/819/1/8

M3 - Article

AN - SCOPUS:84961173489

SN - 0004-637X

VL - 819

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

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ER -

THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS

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