Title:	A High-Resolution foreground model for the MWA EoR1 field: Model and implications for Eor power spectrum analysis
Authors:	Procopio, P. Wayth, R.B. Dwarakanath, K.S. +22 Co-authors
Issue Date:	Aug-2017
Publisher:	Cambridge University Press for Astronomical Society of Australia
Citation:	Publications of the Astronomical Society of Australia, 2017, Vol.34, e033
Abstract:	The current generation of experiments aiming to detect the neutral hydrogen signal from the Epoch of Reionisation (EoR) is likely to be limited by systematic effects associated with removing foreground sources from target fields. In this paper, we develop a model for the compact foreground sources in one of the target fields of the MWA’s EoR key science experiment: the ‘EoR1’ field. The model is based on both the MWA’s GLEAM survey and GMRT 150 MHz data from the TGSS survey, the latter providing higher angular resolution and better astrometric accuracy for compact sources than is available from the MWA alone. The model contains 5 049 sources, some of which have complicated morphology in MWA data, Fornax A being the most complex. The higher resolution data show that 13% of sources that appear point-like to the MWA have complicated morphology such as double and quad structure, with a typical separation of 33 arcsec. We derive an analytic expression for the error introduced into the EoR two-dimensional power spectrum due to peeling close double sources as single point sources and show that for the measured source properties, the error in the power spectrum is confined to high k ⊥ modes that do not affect the overall result for the large-scale cosmological signal of interest. The brightest 10 mis-modelled sources in the field contribute 90% of the power bias in the data, suggesting that it is most critical to improve the models of the brightest sources. With this hybrid model, we reprocess data from the EoR1 field and show a maximum of 8% improved calibration accuracy and a factor of two reduction in residual power in k-space from peeling these sources. Implications for future EoR experiments including the SKA are discussed in relation to the improvements obtained.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/6780
ISSN:	1323-3580 1448-6083(online)
Alternative Location:	http://adsabs.harvard.edu/abs/2017PASA...34...33P http://arxiv.org/abs/1707.02288 http://dx.doi.org/10.1017/pasa.2017.26
Copyright:	2017 Astronomical Society of Australia
Appears in Collections:	Research Papers (A&A)

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