Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array

Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array

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 tri...

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Bibliographic Details
Main Authors: Trott, Cathryn, Watkinson, C.A., Jordan, Chris, Yoshiura, S., Majumdar, S., Barry, Nichole, Byrne, R., Hazelton, B.J., Hasegawa, K., Joseph, R., Kaneuji, T., Kubota, K., Li, W., Line, Jack, Lynch, Christene, McKinley, Ben, Mitchell, D.A., Morales, M.F., Murray, Steven, Pindor, B., Pober, J.C., Rahimi, M., Riding, J., Takahashi, K., Tingay, Steven, Wayth, Randall, Webster, R.L., Wilensky, M., Wyithe, J.S.B., Zheng, Q., Emrich, David, Beardsley, A.P., Booler, Tom, Crosse, B., Franzen, Thomas, Horsley, L., Johnston-Hollitt, Melanie, Kaplan, D.L., Kenney, David, Pallot, D., Sleap, G., Steele, K., Walker, Mia, Williams, Andrew, Wu, C.
Format: Journal Article
Language:English
Published: CAMBRIDGE UNIV PRESS 2019
Subjects:
Science & Technology
Physical Sciences
Astronomy & Astrophysics
cosmology
early universe
instrumentation
methods
statistical
NON-GAUSSIANITY
21-CM
COSMOLOGY
astro-ph.CO
astro-ph.IM
Online Access:https://arxiv.org/abs/1905.07161
http://hdl.handle.net/20.500.11937/91578
Description
Summary: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.

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