Title:	Confirmation of wide-field signatures in redshifted 21 cm power spectra
Authors:	Thyagarajan, Nithyanandan Jacobs, Daniel C Bowman, Judd D. Deshpande, A.A. Sethi, S.K. Srivani, K.S. Subrahmanyan, Ravi Paul, Sourabh Prabu, T. Udaya Shankar, N. +30 Co-authors
Issue Date:	10-Jul-2015
Publisher:	IOP Publishing Ltd for the American Astronomical Society
Citation:	Astrophysical Journal Letters, 2015, Vol. 807, pL-28
Abstract:	We confirm our recent prediction of the “pitchfork” foreground signature in power spectra of high-redshift 21 cm measurements where the interferometer is sensitive to large-scale structure on all baselines. This is due to the inherent response of a wide-field instrument and is characterized by enhanced power from foreground emission in Fourier modes adjacent to those considered to be the most sensitive to the cosmological H i signal. In our recent paper, many signatures from the simulation that predicted this feature were validated against Murchison Widefield Array (MWA) data, but this key pitchfork signature was close to the noise level. In this paper, we improve the data sensitivity through the coherent averaging of 12 independent snapshots with identical instrument settings and provide the first confirmation of the prediction with a signal-to-noise ratio \gt 10. This wide-field effect can be mitigated by careful antenna designs that suppress sensitivity near the horizon. Simple models for antenna apertures that have been proposed for future instruments such as the Hydrogen Epoch of Reionization Array and the Square Kilometre Array indicate they should suppress foreground leakage from the pitchfork by ∼40 dB relative to the MWA and significantly increase the likelihood of cosmological signal detection in these critical Fourier modes in the three-dimensional power spectrum.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/6295
ISSN:	2041-8205 2041-8213 (Online)
Alternative Location:	http://adsabs.harvard.edu/abs/2015ApJ...807L..28T http://arxiv.org/abs/1506.06150 http://dx.doi.org/10.1088/2041-8205/807/2/L28
Copyright:	2015 American Astronomical Society
Appears in Collections:	Research Papers (A&A)

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