Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array. (2019)

• Record Type: Journal Article
• Authors: Trott, Cathryn M.; Watkinson, Catherine A.; Jordan, Christopher H.; Yoshiura, Shintaro; Majumdar, Suman; Barry, N.; Byrne, R.; Hazelton, B. J.; Hasegawa, K.; Joseph, R.; Kaneuji, T.; Kubota, K.; Li, W.; Line, J.; Lynch, C.; McKinley, B.; Mitchell, D. A.; Morales, M. F.; Murray, S.; Pindor, B.; Pober, J. C.; Rahimi, M.; Riding, J.; Takahashi, K.; Tingay, S. J.; Wayth, R. B.; Webster, R. L.; Wilensky, M.; Wyithe, J. S. B.; Zheng, Q.; Emrich, David; Beardsley, A. P.; Booler, T.; Crosse, B.; Franzen, T. M. O.; Horsley, L.; Johnston-Hollitt, M.; Kaplan, D. L.; Kenney, D.; Pallot, D.; Sleap, G.; Steele, K.; Walker, M.; Williams, A.; Wu, C.;
• Is Part Of: Publications of the Astronomical Society of Australia. Volume 36(2019)
• Publication Date: 2019
• Subjects: cosmology, -- early universe, -- instrumentation, -- methods: statistical; Astronomy -- Periodicals; Southern sky (Astronomy) -- Periodicals; Astrophysics -- Periodicals; Periodicals; 520.5
• DOI: 10.1017/pasa.2019.15
• Languages: English
• ISSNs: 1323-3580

Abstract

Abstract: We apply two methods to estimate the 21-cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum estimate to be undertaken on the multiple redundantly spaced triangles of antenna tiles, as well as an estimate based on data gridded to the uv -plane. The direct and gridded bispectrum estimators are applied to 21 h of high-band (167–197 MHz; z = 6.2–7.5) data from the 2016 and 2017 observing seasons. Analytic predictions for the bispectrum bias and variance for point-source foregrounds are derived. We compare the output of these approaches, the foreground contribution to the signal, and future prospects for measuring the bispectra with redundant and non-redundant arrays. We find that some triangle configurations yield bispectrum estimates that are consistent with the expected noise level after 10 h, while equilateral configurations are strongly foreground-dominated. Careful choice of triangle configurations may be made to reduce foreground bias that hinders power spectrum estimators, and the 21-cm bispectrum may be accessible in less time than the 21-cm power spectrum for some wave modes, with detections in hundreds of hours.