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Published November 10, 2023 | Version Published
Journal Article Open

Evidence of Ultrafaint Radio Frequency Interference in Deep 21 cm Epoch of Reionization Power Spectra with the Murchison Wide-field Array

Creators

  • 1. ROR icon University of Manchester
  • 2. ROR icon Queen Mary University of London
  • 3. ROR icon University of Washington
  • 4. ROR icon International Centre for Radio Astronomy Research
  • 5. ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Bentley, Australia
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Arizona State University
  • 8. ROR icon Brown University

Abstract

We present deep upper limits from the 2014 Murchison Widefield Array Phase I observing season, with a particular emphasis on identifying the spectral fingerprints of extremely faint radio frequency interference (RFI) contamination in the 21 cm power spectra (PS). After meticulous RFI excision involving a combination of the SSINS RFI flagger and a series of PS-based jackknife tests, our lowest upper limit on the Epoch of Reionization (EoR) 21 cm PS signal is Δ2 ≤ 1.61 × 104 mK2 at k = 0.258h Mpc−1 at a redshift of 7.1 using 14.7 hr of data. By leveraging our understanding of how even fainter RFI is likely to contaminate the EoR PS, we are able to identify ultrafaint RFI signals in the cylindrical PS. Surprisingly this signature is most obvious in PS formed with less than 1 hr of data, but is potentially subdominant to other systematics in multiple-hour integrations. Since the total RFI budget in a PS detection is quite strict, this nontrivial integration behavior suggests a need to more realistically model coherently integrated ultrafaint RFI in PS measurements so that its potential contribution to a future detection can be diagnosed.

Copyright and License

© 2023. The Author(s). Published by the American Astronomical Society.

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

We acknowledge Jacob Burba, Hugh Garsden, Steven Tingay, and Zheng Zhang for helpful comments. We thank the development teams of pyuvdata, FHD, and ε ppsilon which enabled this work. This work was directly supported by NSF grants AST-1643011, AST- 1613855, OAC-1835421, AST-1506024, AST-1907777, AST-2106510, AST-2107538, AST-2205471, and AST-2228990. This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No. 948764). We acknowledge the University of Washington eScience Institute and UW Research Computing Azure Cloud Credits program for providing computational resources.

This scientific work makes use of the Murchison Radio- astronomy Observatory, operated by CSIRO. 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 native title holders of the Observatory site. Establishment of CSIRO's Murchison Radio-astronomy Observatory is an initiative of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. Support for the operation of the MWA is provided by the Australian Government (NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. This work was supported by resources provided by the Pawsey Supercomputing Research Centre with funding from the Australian Government and the Government of Western Australia.

Funding

This work was directly supported by NSF grants AST-1643011, AST- 1613855, OAC-1835421, AST-1506024, AST-1907777, AST-2106510, AST-2107538, AST-2205471, and AST-2228990. This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No. 948764). 

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Additional details

Additional titles

Alternative title
Evidence of Ultra-faint Radio Frequency Interference in Deep 21~cm Epoch of Reionization Power Spectra with the Murchison Widefield Array

Related works

Is new version of
Discussion Paper: arXiv:2310.03851 (arXiv)

Funding

National Science Foundation
AST-1643011
National Science Foundation
AST-1613855
National Science Foundation
OAC-1835421
National Science Foundation
AST-1506024
National Science Foundation
AST-1907777
National Science Foundation
AST-2106510
National Science Foundation
AST-2107538
National Science Foundation
AST-2205471
National Science Foundation
AST-2228990
European Research Council
948764

Dates

Accepted
2023-10-02
Accepted
Available
2023-11-02
Published

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Publication Status
Published