Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array
May 17, 201919 pages
Published in:
- Publ.Astron.Soc.Austral. 36 (2019) e023
- Published: Jul 18, 2019
e-Print:
- 1905.07161 [astro-ph.CO]
DOI:
- 10.1017/pasa.2019.15 (publication)
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Abstract: (Cambridge University Press)
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.Note:
- 19 pages, 10 figures, accepted for publication in PASA
- cosmology
- early universe
- instrumentation
- methods: statistical
References(50)
Figures(10)