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Scintillation noise power spectrum and its impact on high-redshift 21-cm observations

Vedantham, H. K. and Koopmans, L. V. E. (2016) Scintillation noise power spectrum and its impact on high-redshift 21-cm observations. Monthly Notices of the Royal Astronomical Society, 458 (3). pp. 3099-3117. ISSN 0035-8711.

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Visibility scintillation resulting from wave propagation through the turbulent ionosphere can be an important source of noise at low radio frequencies (ν ≲ 200 MHz). Many low-frequency experiments are underway to detect the power spectrum of brightness temperature fluctuations of the neutral-hydrogen 21-cm signal from the Epoch of Reionization (EoR: 12 ≳ z ≳ 7, 100 ≲ ν ≲ 175 MHz). In this paper, we derive scintillation noise power spectra in such experiments while taking into account the effects of typical data processing operations such as self-calibration and Fourier synthesis. We find that for minimally redundant arrays such as LOFAR and MWA, scintillation noise is of the same order of magnitude as thermal noise, has a spectral coherence dictated by stretching of the snapshot uv-coverage with frequency, and thus is confined to the well-known wedge-like structure in the cylindrical (two-dimensional) power spectrum space. Compact, fully redundant (d_(core) ≲ r_F ≈ 300 m at 150 MHz) arrays such as HERA and SKA-LOW (core) will be scintillation noise dominated at all baselines, but the spatial and frequency coherence of this noise will allow it to be removed along with spectrally smooth foregrounds.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Vedantham, H. K.0000-0002-0872-181X
Koopmans, L. V. E.0000-0003-1840-0312
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 February 22. Received 2016 February 22; in original form 2015 November 12. First published online February 26, 2016. The authors thank Dr Maaijke Mevius and Professor A.G. de Bruyn for many interesting discussions. The authors also acknowledge the financial support from the European Research Council under ERC-Starting Grant FIRSTLIGHT - 258942.
Funding AgencyGrant Number
European Research Council (ERC)258942
Subject Keywords:atmospheric effects methods: analytical methods: statistical techniques: interferometric dark ages, reionization, first stars
Issue or Number:3
Record Number:CaltechAUTHORS:20160603-070423761
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Official Citation:H. K. Vedantham and L. V. E. Koopmans Scintillation noise power spectrum and its impact on high-redshift 21-cm observations MNRAS (May 21, 2016) Vol. 458 3099-3117 doi:10.1093/mnras/stw443 first published online February 26, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67632
Deposited By: Ruth Sustaita
Deposited On:03 Jun 2016 17:26
Last Modified:03 Oct 2019 10:07

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