Journal article

Empirical covariance modeling for 21 cm power spectrum estimation: A method demonstration and new limits from early Murchison Widefield Array 128-tile data

Joshua S Dillon, Abraham R Neben, Jacqueline N Hewitt, Max Tegmark, N Barry, AP Beardsley, JD Bowman, F Briggs, P Carroll, A de Oliveira-Costa, A Ewall-Wice, L Feng, LJ Greenhill, BJ Hazelton, L Hernquist, N Hurley-Walker, DC Jacobs, HS Kim, P Kittiwisit, E Lenc Show all



The separation of the faint cosmological background signal from bright astrophysical foregrounds remains one of the most daunting challenges of mapping the high-redshift intergalactic medium with the redshifted 21 cm line of neutral hydrogen. Advances in mapping and modeling of diffuse and point source foregrounds have improved subtraction accuracy, but no subtraction scheme is perfect. Precisely quantifying the errors and error correlations due to missubtracted foregrounds allows for both the rigorous analysis of the 21 cm power spectrum and for the maximal isolation of the "EoR window" from foreground contamination. We present a method to infer the covariance of foreground residuals from t..

View full abstract


Awarded by NSF

Awarded by U.S. National Science Foundation

Awarded by Australian Research Council (LIEF Grants)

Awarded by U.S. Air Force Office of Scientific Research

Awarded by Centre for All-sky Astrophysics (an Australian Research Council Centre of Excellence)

Awarded by Victoria University of Wellington (New Zealand Ministry of Economic Development)

Awarded by Division Of Astronomical Sciences

Funding Acknowledgements

We would like to thank Adrian Liu, Aaron Parsons, and Jeff Zheng for helpful discussions. We also acknowledge an anonymous referee whose insightful questions led to the refinement of method in order to a bias that occurs when a uv cell is used to estimate its own covariance and the ultimate form of Eq. (10). We would also like to thank Rennan Barkana for the theoretical power spectra in Fig. 9. This work was supported by NSF Grants No. AST-0457585, No. AST-0821321, No. AST-1105835, No. AST-1410719, No. AST-1410484, No. AST-1411622, and No. AST-1440343, by the MIT School of Science, by the Marble Astrophysics Fund, and by generous donations from Jonathan Rothberg and an anonymous donor. D. C. J. would like to acknowledge NSF support under Grant No. AST-1401708. This scientific work makes use of the Murchison Radio-astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site. Support for the MWA comes from the U.S. National Science Foundation (Grants No. AST-0457585, No. PHY-0835713, No. CAREER-0847753, and No. AST-0908884), the Australian Research Council (LIEF Grants No. LE0775621 and No. LE0882938), the U.S. Air Force Office of Scientific Research (Grant No. FA9550-0510247), and the Centre for All-sky Astrophysics (an Australian Research Council Centre of Excellence funded by Grant No. CE110001020). Support is also provided by the Smithsonian Astrophysical Observatory, the MIT School of Science, the Raman Research Institute, the Australian National University, and the Victoria University of Wellington (via Grant No. MED-E1799 from the New Zealand Ministry of Economic Development and an IBM Shared University Research Grant). The Australian Federal government provides additional support via the Commonwealth Scientific and Industrial Research Organisation (CSIRO), National Collaborative Research Infrastructure Strategy, Education Investment Fund, and the Australia India Strategic Research Fund, and Astronomy Australia Limited, under contract to Curtin University. We acknowledge the iVEC Petabyte Data Store, the Initiative in Innovative Computing, and the CUDA Center for Excellence sponsored by NVIDIA at Harvard University, and the International Centre for Radio Astronomy Research (ICRAR), a Joint Venture of Curtin University and The University of Western Australia, funded by the Western Australian State government.