Journal
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA
Volume 36, Issue -, Pages -Publisher
CAMBRIDGE UNIV PRESS
DOI: 10.1017/pasa.2019.15
Keywords
cosmology; early universe; instrumentation; methods; statistical
Categories
Funding
- Australian Research Council Centre of Excellence [CE170100013]
- ARC Future Fellowship [FT180100196]
- European Research Council under ERC [638743-FIRSTDAWN]
- Ministry of Education, Culture, Sports, and Science and Technology (MEXT) of Japan [15H05896, 16H05999, 17H01110]
- Bilateral Joint Research Projects of JSPS
- Western Australian State government
- Australian Research Council LIEF [LE160100031]
- Dunlap Institute for Astronomy and Astrophysics at the University of Toronto
- Australian Government (NCRIS)
- Western Australian and Australian Governments
- Australian Research Council [LE160100031] Funding Source: Australian Research Council
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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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