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Decontamination of cosmological 21-cm maps

Gleser, Liron and Nusser, Adi and Benson, Andrew J. (2008) Decontamination of cosmological 21-cm maps. Monthly Notices of the Royal Astronomical Society, 391 (1). pp. 383-398. ISSN 0035-8711. doi:10.1111/j.1365-2966.2008.13897.x.

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We present a method for extracting the expected cosmological 21-cm signal from the epoch of re-ionization, taking into account contaminating radiations and random instrumental noise. The method is based on the maximum a posteriori probability (MAP) formalism and employs the coherence of the contaminating radiation along the line-of-sight and the three-dimensional correlations of the cosmological signal. We test the method using a detailed and comprehensive modelling of the cosmological 21-cm signal and the contaminating radiation. The signal is obtained using a high-resolution N-body simulation where the gas is assumed to trace the dark matter and is re-ionized by stellar radiation computed from semi-analytic galaxy formation recipes. We model contaminations to the cosmological signal from synchrotron and free–free galactic foregrounds and extragalactic sources including active galactic nuclei, radio haloes and relics, synchrotron and free–free emission from star-forming galaxies and free–free emission from dark matter haloes and the intergalactic medium. We provide tests of the reconstruction method for several rms values of instrumental noise from σN= 1 to 250 mK. For low instrumental noise, the recovered signal, along individual lines-of-sight, fits the true cosmological signal with a mean rms difference of drms≈ 1.7 ± 0.6 for σN= 1 mK, and drms≈ 4.2 ± 0.4 for σN= 5 mK. The one-dimensional power spectrum is nicely reconstructed for all values of σN considered here, while the reconstruction of the two-dimensional power spectrum and the Minkowski functionals is good only for noise levels of the order of few mK.

Item Type:Article
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Benson, Andrew J.0000-0001-5501-6008
Additional Information:© 2008 The Authors. Journal compilation © 2008 RAS. Accepted 2008 August 29. Received 2008 August 27; in original form 2007 December 4. Published Online: 17 October 2008. LG and AN acknowledge the support of the Asher Space Research Institute and the German Israeli Foundation for the Development of Research. AJB acknowledges support from the Gordon & Betty Moore Foundation.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Asher Space Research InstituteUNSPECIFIED
German Israeli Foundation for the Development of ResearchUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:intergalactic medium; cosmology: theory; diffuse radiation; large-scale structure of Universe; radio lines: general
Issue or Number:1
Record Number:CaltechAUTHORS:GLEmnras08
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Official Citation:Liron Gleser, Adi Nusser, and Andrew J. Benson Decontamination of cosmological 21-cm maps MNRAS (2008) Vol. 391 383-398 doi:10.1111/j.1365-2966.2008.13897.x First published online November 21, 2008
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13250
Deposited By: Tony Diaz
Deposited On:05 Feb 2009 20:55
Last Modified:08 Nov 2021 22:36

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