| Title: |
Improved Limits on the 21 cm Signal at z = 6.5-7.0 with the Murchison Widefield Array Using Gaussian Information |
| Authors: |
Trott, Cathryn 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.; Jong, E.; Kolopanis, M.; Kunicki, T.; Lilleskov, E.; Morales, M. F.; Pober, J.; Selvaraj, A.; Shi, R.; Takahashi, K.; Tingay, S. J.; Webster, R. L.; Yoshiura, S.; Zheng, Q. |
| Source: |
Astrophysical Journal |
| Publication Year: |
2025 |
| Collection: |
Australian National University: ANU Digital Collections |
| Description: |
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. ; We thank the reviewer of this paper, for rigorous examination of the work and its consequent improvement. This research was partly supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. The International Centre for Radio Astronomy Research (ICRAR) is a Joint Venture of Curtin University and The University of Western Australia, funded by the Western Australian State government. This scientific work uses data obtained from Inyarrimanha Ilgari Bundara/the Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji People as the Traditional Owners and ... |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
https://hdl.handle.net/1885/733796234; 105017465557 |
| DOI: |
10.3847/1538-4357/adff80 |
| Availability: |
https://hdl.handle.net/1885/733796234; https://doi.org/10.3847/1538-4357/adff80; https://openresearch-repository.anu.edu.au/bitstreams/8a4079be-e43c-4cdd-a0ca-a7c1eaeb0d29/download; https://openresearch-repository.anu.edu.au/bitstreams/87906e13-bbd4-437c-8f48-5b8236f0a132/download |
| Rights: |
© 2025. The Author(s). |
| Accession Number: |
edsbas.A07DD3CA |
| Database: |
BASE |