Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR

A. H. Patil; S. Yatawatta; L. V.E. Koopmans; A. G.De Bruyn; M. A. Brentjens; S. Zaroubi; K. M.B. Asad; M. Hatef; V. Jelić; M. Mevius; A. R. Offringa; V. N. Pandey; H. Vedantham; F. B. Abdalla; W. N. Brouw; E. Chapman; B. Ciardi; B. K. Gehlot; A. Ghosh; G. Harker; I. T. Iliev; K. Kakiichi; S. Majumdar; G. Mellema; M. B. Silva; J. Schaye; D. Vrbanec; S. J. Wijnholds

doi:10.3847/1538-4357/aa63e7

Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR

A. H. Patil, S. Yatawatta, L. V.E. Koopmans, A. G.De Bruyn, M. A. Brentjens, S. Zaroubi, K. M.B. Asad, M. Hatef, V. Jelić, M. Mevius, A. R. Offringa, V. N. Pandey, H. Vedantham, F. B. Abdalla, W. N. Brouw, E. Chapman, B. Ciardi, B. K. Gehlot, A. Ghosh, G. HarkerI. T. Iliev, K. Kakiichi, S. Majumdar, G. Mellema, M. B. Silva, J. Schaye, D. Vrbanec, S. J. Wijnholds

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Abstract

We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9-10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero δ² ₁ = (56 ± 13 mK)²(1-σ) excess variance and a best 2-σ upper limit of δ² ₂₁ <(79.6 mK)²at k = 0.053 h cMpc^-1 in the range z = 9.6-10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.

Original language	English
Article number	65
Journal	Astrophysical Journal
Volume	838
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/aa63e7
State	Published - 20 Mar 2017

Bibliographical note

Funding Information:
I.T.I. was supported by the Science and Technology Facilities Council (grant number ST/I000976/1). S.M. would like to acknowledge the financial assistance from the European Research Council under ERC grant number 638743-FIRSTDAWN and from the European Unions Seventh Framework Programme FP7-PEOPLE-2012-CIG grant number 321933-21ALPHA.

Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.

Keywords

dark ages
first stars
reionization

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10.3847/1538-4357/aa63e7

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Patil, A. H., Yatawatta, S., Koopmans, L. V. E., Bruyn, A. G. D., Brentjens, M. A., Zaroubi, S., Asad, K. M. B., Hatef, M., Jelić, V., Mevius, M., Offringa, A. R., Pandey, V. N., Vedantham, H., Abdalla, F. B., Brouw, W. N., Chapman, E., Ciardi, B., Gehlot, B. K., Ghosh, A., ... Wijnholds, S. J. (2017). Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR. Astrophysical Journal, 838(1), [65]. https://doi.org/10.3847/1538-4357/aa63e7

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abstract = "We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9-10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero δ2 1 = (56 ± 13 mK)2(1-σ) excess variance and a best 2-σ upper limit of δ2 21 <(79.6 mK)2at k = 0.053 h cMpc-1 in the range z = 9.6-10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.",

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author = "Patil, {A. H.} and S. Yatawatta and Koopmans, {L. V.E.} and Bruyn, {A. G.De} and Brentjens, {M. A.} and S. Zaroubi and Asad, {K. M.B.} and M. Hatef and V. Jeli{\'c} and M. Mevius and Offringa, {A. R.} and Pandey, {V. N.} and H. Vedantham and Abdalla, {F. B.} and Brouw, {W. N.} and E. Chapman and B. Ciardi and Gehlot, {B. K.} and A. Ghosh and G. Harker and Iliev, {I. T.} and K. Kakiichi and S. Majumdar and G. Mellema and Silva, {M. B.} and J. Schaye and D. Vrbanec and Wijnholds, {S. J.}",

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Patil, AH, Yatawatta, S, Koopmans, LVE, Bruyn, AGD, Brentjens, MA, Zaroubi, S, Asad, KMB, Hatef, M, Jelić, V, Mevius, M, Offringa, AR, Pandey, VN, Vedantham, H, Abdalla, FB, Brouw, WN, Chapman, E, Ciardi, B, Gehlot, BK, Ghosh, A, Harker, G, Iliev, IT, Kakiichi, K, Majumdar, S, Mellema, G, Silva, MB, Schaye, J, Vrbanec, D & Wijnholds, SJ 2017, 'Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR', Astrophysical Journal, vol. 838, no. 1, 65. https://doi.org/10.3847/1538-4357/aa63e7

TY - JOUR

T1 - Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR

AU - Patil, A. H.

AU - Yatawatta, S.

AU - Koopmans, L. V.E.

AU - Bruyn, A. G.De

AU - Brentjens, M. A.

AU - Zaroubi, S.

AU - Asad, K. M.B.

AU - Hatef, M.

AU - Jelić, V.

AU - Mevius, M.

AU - Offringa, A. R.

AU - Pandey, V. N.

AU - Vedantham, H.

AU - Abdalla, F. B.

AU - Brouw, W. N.

AU - Chapman, E.

AU - Ciardi, B.

AU - Gehlot, B. K.

AU - Ghosh, A.

AU - Harker, G.

AU - Iliev, I. T.

AU - Kakiichi, K.

AU - Majumdar, S.

AU - Mellema, G.

AU - Silva, M. B.

AU - Schaye, J.

AU - Vrbanec, D.

AU - Wijnholds, S. J.

PY - 2017/3/20

Y1 - 2017/3/20

N2 - We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9-10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero δ2 1 = (56 ± 13 mK)2(1-σ) excess variance and a best 2-σ upper limit of δ2 21 <(79.6 mK)2at k = 0.053 h cMpc-1 in the range z = 9.6-10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.

AB - We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9-10.6, using the Low-Frequency Array (LOFAR) High-Band Antenna (HBA). In total, 13.0 hr of data were used from observations centered on the North Celestial Pole. After subtraction of the sky model and the noise bias, we detect a non-zero δ2 1 = (56 ± 13 mK)2(1-σ) excess variance and a best 2-σ upper limit of δ2 21 <(79.6 mK)2at k = 0.053 h cMpc-1 in the range z = 9.6-10.6. The excess variance decreases when optimizing the smoothness of the direction- and frequency-dependent gain calibration, and with increasing the completeness of the sky model. It is likely caused by (i) residual side-lobe noise on calibration baselines, (ii) leverage due to nonlinear effects, (iii) noise and ionosphere-induced gain errors, or a combination thereof. Further analyses of the excess variance will be discussed in forthcoming publications.

KW - dark ages

KW - first stars

KW - reionization

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VL - 838

JO - Astrophysical Journal

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ER -

Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR

Abstract

Bibliographical note

Keywords

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