Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information

Cathryn M. Trott; C. D. Nunhokee; D. Null; N. Barry; Y. Qin; R. B. Wayth; J. L.B. Line; C. H. Jordan; B. Pindor; J. H. Cook; J. Bowman; A. Chokshi; J. Ducharme; K. Elder; Q. Guo; B. J. Hazelton; W. Hidayat; T. Ito; D. Jacobs; E. Jong; M. Kolopanis; T. Kunicki; E. Lilleskov; M. F. Morales; J. Pober; A. Selvaraj; R. Shi; K. Takahashi; S. J. Tingay; R. L. Webster; S. Yoshiura; Q. Zheng

doi:10.3847/1538-4357/adff80

Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information

Cathryn M. Trott^*, C. D. Nunhokee, D. Null, N. Barry, Y. Qin, R. B. Wayth, J. L.B. Line, C. H. Jordan, B. Pindor, J. H. Cook, J. Bowman, A. Chokshi, J. Ducharme, K. Elder, Q. Guo, B. J. Hazelton, W. Hidayat, T. Ito, D. Jacobs, E. JongM. Kolopanis, T. Kunicki, E. Lilleskov, M. F. Morales, J. Pober, A. Selvaraj, R. Shi, K. Takahashi, S. J. Tingay, R. L. Webster, S. Yoshiura, Q. Zheng

^*Corresponding author for this work

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

Abstract

We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK)² to (23.0 mK)² at z = 6.5 for the East-West polarization, and from (39.2 mK)² to (21.7 mK)² = 470 mK² in North-South. The best limits at z = 6.8 (z = 7.0) improve to P < (25.9 mK)² (P < (32.0 mK)²) and k = 0.18h Mpc⁻¹ (k = 0.21h Mpc⁻¹). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.

Original language	English
Article number	211
Number of pages	10
Journal	Astrophysical Journal
Volume	991
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/adff80
Publication status	Published - 1 Oct 2025

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Trott, C. M., Nunhokee, C. D., Null, D., Barry, N., Qin, Y., Wayth, R. B., Line, J. L. B., Jordan, C. H., Pindor, B., Cook, J. H., Bowman, J., Chokshi, A., Ducharme, J., Elder, K., Guo, Q., Hazelton, B. J., Hidayat, W., Ito, T., Jacobs, D., ... Zheng, Q. (2025). Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information. Astrophysical Journal, 991(2), Article 211. https://doi.org/10.3847/1538-4357/adff80

@article{455ba10f6a7a43f6ad3dfb6493e93ef2,

title = "Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information",

abstract = "We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK)2 to (23.0 mK)2 at z = 6.5 for the East-West polarization, and from (39.2 mK)2 to (21.7 mK)2 = 470 mK2 in North-South. The best limits at z = 6.8 (z = 7.0) improve to P < (25.9 mK)2 (P < (32.0 mK)2) and k = 0.18h Mpc−1 (k = 0.21h Mpc−1). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.",

author = "Trott, \{Cathryn M.\} and Nunhokee, \{C. D.\} and D. Null and N. Barry and Y. Qin and Wayth, \{R. B.\} and Line, \{J. L.B.\} and Jordan, \{C. H.\} and B. Pindor and Cook, \{J. H.\} and J. Bowman and A. Chokshi and J. Ducharme and K. Elder and Q. Guo and Hazelton, \{B. J.\} and W. Hidayat and T. Ito and D. Jacobs and E. Jong and M. Kolopanis and T. Kunicki and E. Lilleskov and Morales, \{M. F.\} and J. Pober and A. Selvaraj and R. Shi and K. Takahashi and Tingay, \{S. J.\} and Webster, \{R. L.\} and S. Yoshiura and Q. Zheng",

note = " {\textcopyright} 2025. The Author(s). ",

year = "2025",

month = oct,

day = "1",

doi = "10.3847/1538-4357/adff80",

language = "English",

volume = "991",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

}

Trott, CM, Nunhokee, CD, Null, D, Barry, N, Qin, Y, Wayth, RB, Line, JLB, Jordan, CH, Pindor, B, Cook, JH, Bowman, J, Chokshi, A, Ducharme, J, Elder, K, Guo, Q, Hazelton, BJ, Hidayat, W, Ito, T, Jacobs, D, Jong, E, Kolopanis, M, Kunicki, T, Lilleskov, E, Morales, MF, Pober, J, Selvaraj, A, Shi, R, Takahashi, K, Tingay, SJ, Webster, RL, Yoshiura, S & Zheng, Q 2025, 'Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information', Astrophysical Journal, vol. 991, no. 2, 211. https://doi.org/10.3847/1538-4357/adff80

TY - JOUR

T1 - Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information

AU - Trott, Cathryn M.

AU - Nunhokee, C. D.

AU - Null, D.

AU - Barry, N.

AU - Qin, Y.

AU - Wayth, R. B.

AU - Line, J. L.B.

AU - Jordan, C. H.

AU - Pindor, B.

AU - Cook, J. H.

AU - Bowman, J.

AU - Chokshi, A.

AU - Ducharme, J.

AU - Elder, K.

AU - Guo, Q.

AU - Hazelton, B. J.

AU - Hidayat, W.

AU - Ito, T.

AU - Jacobs, D.

AU - Jong, E.

AU - Kolopanis, M.

AU - Kunicki, T.

AU - Lilleskov, E.

AU - Morales, M. F.

AU - Pober, J.

AU - Selvaraj, A.

AU - Shi, R.

AU - Takahashi, K.

AU - Tingay, S. J.

AU - Webster, R. L.

AU - Yoshiura, S.

AU - Zheng, Q.

PY - 2025/10/1

Y1 - 2025/10/1

N2 - We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK)2 to (23.0 mK)2 at z = 6.5 for the East-West polarization, and from (39.2 mK)2 to (21.7 mK)2 = 470 mK2 in North-South. The best limits at z = 6.8 (z = 7.0) improve to P < (25.9 mK)2 (P < (32.0 mK)2) and k = 0.18h Mpc−1 (k = 0.21h Mpc−1). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.

AB - We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK)2 to (23.0 mK)2 at z = 6.5 for the East-West polarization, and from (39.2 mK)2 to (21.7 mK)2 = 470 mK2 in North-South. The best limits at z = 6.8 (z = 7.0) improve to P < (25.9 mK)2 (P < (32.0 mK)2) and k = 0.18h Mpc−1 (k = 0.21h Mpc−1). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.

UR - https://www.scopus.com/pages/publications/105017465557

U2 - 10.3847/1538-4357/adff80

DO - 10.3847/1538-4357/adff80

M3 - Article

AN - SCOPUS:105017465557

SN - 0004-637X

VL - 991

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 211

ER -

Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information

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