First limits on the 21 cm power spectrum during the Epoch of X-ray heating

A. Ewall-Wice, Joshua S. Dillon, J. N. Hewitt, A. Loeb, A. Mesinger, A. R. Neben, A. R. Offringa, M. Tegmark, N. Barry, A. P. Beardsley, G. Bernardi, Judd Bowman, F. Briggs, R. J. Cappallo, P. Carroll, B. E. Corey, A. de Oliveira-Costa, D. Emrich, L. Feng, B. M. Gaensler & 45 others R. Goeke, L. J. Greenhill, B. J. Hazelton, N. Hurley-Walker, M. Johnston-Hollitt, Daniel Jacobs, D. L. Kaplan, J. C. Kasper, H. S. Kim, E. Kratzenberg, E. Lenc, J. Line, C. J. Lonsdale, M. J. Lynch, B. McKinley, S. R. McWhirter, D. A. Mitchell, M. F. Morales, E. Morgan, Nithyanandan Thyagarajan, D. Oberoi, S. M. Ord, S. Paul, B. Pindor, J. C. Pober, T. Prabu, P. Procopio, J. Riding, A. E E Rogers, A. Roshi, N. Udaya Shankar, Shiv K. Sethi, K. S. Srivani, R. Subrahmanyan, I. S. Sullivan, S. J. Tingay, C. M. Trott, M. Waterson, R. B. Wayth, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, C. Wu, J. S B Wyithe

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FMband, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k≲0.5 h Mpc-1. This represents the first upper limits on the 21 cmpower spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

Original languageEnglish (US)
Pages (from-to)4320-4347
Number of pages28
JournalMonthly Notices of the Royal Astronomical Society
Volume460
Issue number4
DOIs
StatePublished - Aug 21 2016

Fingerprint

power spectra
time measurement
heating
ionospheres
contamination
radio
resin film infusion
calibration
radio frequency interference
ionosphere
x rays
radio observation
brightness temperature
systematic errors
night
ionospherics
autocorrelation
cosmology
observatories
low frequencies

Keywords

  • Dark ages, reionization, first stars
  • Radio lines: general
  • Techniques: interferometric
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Ewall-Wice, A., Dillon, J. S., Hewitt, J. N., Loeb, A., Mesinger, A., Neben, A. R., ... Wyithe, J. S. B. (2016). First limits on the 21 cm power spectrum during the Epoch of X-ray heating. Monthly Notices of the Royal Astronomical Society, 460(4), 4320-4347. https://doi.org/10.1093/mnras/stw1022

First limits on the 21 cm power spectrum during the Epoch of X-ray heating. / Ewall-Wice, A.; Dillon, Joshua S.; Hewitt, J. N.; Loeb, A.; Mesinger, A.; Neben, A. R.; Offringa, A. R.; Tegmark, M.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hurley-Walker, N.; Johnston-Hollitt, M.; Jacobs, Daniel; Kaplan, D. L.; Kasper, J. C.; Kim, H. S.; Kratzenberg, E.; Lenc, E.; Line, J.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Thyagarajan, Nithyanandan; Oberoi, D.; Ord, S. M.; Paul, S.; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E E; Roshi, A.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S B.

In: Monthly Notices of the Royal Astronomical Society, Vol. 460, No. 4, 21.08.2016, p. 4320-4347.

Research output: Contribution to journalArticle

Ewall-Wice, A, Dillon, JS, Hewitt, JN, Loeb, A, Mesinger, A, Neben, AR, Offringa, AR, Tegmark, M, Barry, N, Beardsley, AP, Bernardi, G, Bowman, J, Briggs, F, Cappallo, RJ, Carroll, P, Corey, BE, de Oliveira-Costa, A, Emrich, D, Feng, L, Gaensler, BM, Goeke, R, Greenhill, LJ, Hazelton, BJ, Hurley-Walker, N, Johnston-Hollitt, M, Jacobs, D, Kaplan, DL, Kasper, JC, Kim, HS, Kratzenberg, E, Lenc, E, Line, J, Lonsdale, CJ, Lynch, MJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Thyagarajan, N, Oberoi, D, Ord, SM, Paul, S, Pindor, B, Pober, JC, Prabu, T, Procopio, P, Riding, J, Rogers, AEE, Roshi, A, Udaya Shankar, N, Sethi, SK, Srivani, KS, Subrahmanyan, R, Sullivan, IS, Tingay, SJ, Trott, CM, Waterson, M, Wayth, RB, Webster, RL, Whitney, AR, Williams, A, Williams, CL, Wu, C & Wyithe, JSB 2016, 'First limits on the 21 cm power spectrum during the Epoch of X-ray heating', Monthly Notices of the Royal Astronomical Society, vol. 460, no. 4, pp. 4320-4347. https://doi.org/10.1093/mnras/stw1022
Ewall-Wice, A. ; Dillon, Joshua S. ; Hewitt, J. N. ; Loeb, A. ; Mesinger, A. ; Neben, A. R. ; Offringa, A. R. ; Tegmark, M. ; Barry, N. ; Beardsley, A. P. ; Bernardi, G. ; Bowman, Judd ; Briggs, F. ; Cappallo, R. J. ; Carroll, P. ; Corey, B. E. ; de Oliveira-Costa, A. ; Emrich, D. ; Feng, L. ; Gaensler, B. M. ; Goeke, R. ; Greenhill, L. J. ; Hazelton, B. J. ; Hurley-Walker, N. ; Johnston-Hollitt, M. ; Jacobs, Daniel ; Kaplan, D. L. ; Kasper, J. C. ; Kim, H. S. ; Kratzenberg, E. ; Lenc, E. ; Line, J. ; Lonsdale, C. J. ; Lynch, M. J. ; McKinley, B. ; McWhirter, S. R. ; Mitchell, D. A. ; Morales, M. F. ; Morgan, E. ; Thyagarajan, Nithyanandan ; Oberoi, D. ; Ord, S. M. ; Paul, S. ; Pindor, B. ; Pober, J. C. ; Prabu, T. ; Procopio, P. ; Riding, J. ; Rogers, A. E E ; Roshi, A. ; Udaya Shankar, N. ; Sethi, Shiv K. ; Srivani, K. S. ; Subrahmanyan, R. ; Sullivan, I. S. ; Tingay, S. J. ; Trott, C. M. ; Waterson, M. ; Wayth, R. B. ; Webster, R. L. ; Whitney, A. R. ; Williams, A. ; Williams, C. L. ; Wu, C. ; Wyithe, J. S B. / First limits on the 21 cm power spectrum during the Epoch of X-ray heating. In: Monthly Notices of the Royal Astronomical Society. 2016 ; Vol. 460, No. 4. pp. 4320-4347.
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abstract = "We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FMband, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k≲0.5 h Mpc-1. This represents the first upper limits on the 21 cmpower spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.",
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TY - JOUR

T1 - First limits on the 21 cm power spectrum during the Epoch of X-ray heating

AU - Ewall-Wice, A.

AU - Dillon, Joshua S.

AU - Hewitt, J. N.

AU - Loeb, A.

AU - Mesinger, A.

AU - Neben, A. R.

AU - Offringa, A. R.

AU - Tegmark, M.

AU - Barry, N.

AU - Beardsley, A. P.

AU - Bernardi, G.

AU - Bowman, Judd

AU - Briggs, F.

AU - Cappallo, R. J.

AU - Carroll, P.

AU - Corey, B. E.

AU - de Oliveira-Costa, A.

AU - Emrich, D.

AU - Feng, L.

AU - Gaensler, B. M.

AU - Goeke, R.

AU - Greenhill, L. J.

AU - Hazelton, B. J.

AU - Hurley-Walker, N.

AU - Johnston-Hollitt, M.

AU - Jacobs, Daniel

AU - Kaplan, D. L.

AU - Kasper, J. C.

AU - Kim, H. S.

AU - Kratzenberg, E.

AU - Lenc, E.

AU - Line, J.

AU - Lonsdale, C. J.

AU - Lynch, M. J.

AU - McKinley, B.

AU - McWhirter, S. R.

AU - Mitchell, D. A.

AU - Morales, M. F.

AU - Morgan, E.

AU - Thyagarajan, Nithyanandan

AU - Oberoi, D.

AU - Ord, S. M.

AU - Paul, S.

AU - Pindor, B.

AU - Pober, J. C.

AU - Prabu, T.

AU - Procopio, P.

AU - Riding, J.

AU - Rogers, A. E E

AU - Roshi, A.

AU - Udaya Shankar, N.

AU - Sethi, Shiv K.

AU - Srivani, K. S.

AU - Subrahmanyan, R.

AU - Sullivan, I. S.

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 - Wu, C.

AU - Wyithe, J. S B

PY - 2016/8/21

Y1 - 2016/8/21

N2 - We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FMband, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k≲0.5 h Mpc-1. This represents the first upper limits on the 21 cmpower spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

AB - We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FMband, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k≲0.5 h Mpc-1. This represents the first upper limits on the 21 cmpower spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

KW - Dark ages, reionization, first stars

KW - Radio lines: general

KW - Techniques: interferometric

KW - X-rays: galaxies

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