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 & 49 others 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

Research output: Contribution to journalArticle

36 Citations (Scopus)

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 languageEnglish (US)
Article number8
JournalAstrophysical Journal
Volume819
Issue number1
DOIs
StatePublished - Mar 1 2016

Fingerprint

cosmology
power spectra
field of view
time measurement
sidelobes
sky
experiment
completeness
heuristics
subtraction
simulation
contamination
recovery
formalism
removal

Keywords

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

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Pober, J. C., Hazelton, B. J., Beardsley, A. P., Barry, N. A., Martinot, Z. E., Sullivan, I. S., ... 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), [8]. https://doi.org/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. / 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, Judd; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; De Oliveira-Costa, A.; Deshpande, A. A.; Dillon, Joshua S.; Emrich, D.; Ewall-Wice, A. M.; Feng, L.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hindson, L.; Hurley-Walker, N.; Jacobs, Daniel; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, Han Seek; Kittiwisit, P.; Kratzenberg, E.; Kudryavtseva, N.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morgan, E.; Neben, A. R.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, Sourabh; Pindor, B.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E E; Roshi, A.; Sethi, Shiv K.; Shankar, N. Udaya; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Thyagarajan, Nithyanandan; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wyithe, J. S B.

In: Astrophysical Journal, Vol. 819, No. 1, 8, 01.03.2016.

Research output: Contribution to journalArticle

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
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, Judd ; Briggs, F. ; Cappallo, R. J. ; Carroll, P. ; Corey, B. E. ; De Oliveira-Costa, A. ; Deshpande, A. A. ; Dillon, Joshua S. ; Emrich, D. ; Ewall-Wice, A. M. ; Feng, L. ; Goeke, R. ; Greenhill, L. J. ; Hewitt, J. N. ; Hindson, L. ; Hurley-Walker, N. ; Jacobs, Daniel ; Johnston-Hollitt, M. ; Kaplan, D. L. ; Kasper, J. C. ; Kim, Han Seek ; Kittiwisit, P. ; Kratzenberg, E. ; Kudryavtseva, N. ; Lenc, E. ; Line, J. ; Loeb, A. ; Lonsdale, C. J. ; Lynch, M. J. ; McKinley, B. ; McWhirter, S. R. ; Mitchell, D. A. ; Morgan, E. ; Neben, A. R. ; Oberoi, D. ; Offringa, A. R. ; Ord, S. M. ; Paul, Sourabh ; Pindor, B. ; Prabu, T. ; Procopio, P. ; Riding, J. ; Rogers, A. E E ; Roshi, A. ; Sethi, Shiv K. ; Shankar, N. Udaya ; Srivani, K. S. ; Subrahmanyan, R. ; Tegmark, M. ; Thyagarajan, Nithyanandan ; Tingay, S. J. ; Trott, C. M. ; Waterson, M. ; Wayth, R. B. ; Webster, R. L. ; Whitney, A. R. ; Williams, A. ; Williams, C. L. ; Wyithe, J. S B. / THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY : A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS. In: Astrophysical Journal. 2016 ; Vol. 819, No. 1.
@article{69709da6a76747c49dc1b06af7c73a48,
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 = "3",
day = "1",
doi = "10.3847/0004-637X/819/1/8",
language = "English (US)",
volume = "819",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

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

UR - http://www.scopus.com/inward/record.url?scp=84961173489&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84961173489&partnerID=8YFLogxK

U2 - 10.3847/0004-637X/819/1/8

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

M3 - Article

VL - 819

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 8

ER -