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Title: EXPLORING THE COSMIC REIONIZATION EPOCH IN FREQUENCY SPACE: AN IMPROVED APPROACH TO REMOVE THE FOREGROUND IN 21 cm TOMOGRAPHY

Abstract

With the intent of correctly restoring the redshifted 21 cm signals emitted by neutral hydrogen during the cosmic reionization processes, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency space in order to investigate whether they work satisfactorily with complex foreground by quantitatively evaluating the quality of restored 21 cm signals in terms of sample statistics. We construct the foreground model to characterize both spatial and spectral substructures of the real sky, and use it to simulate the observed radio spectra. By comparing between different separation approaches through statistical analysis of restored 21 cm spectra and corresponding power spectra, as well as their constraints on the mean halo bias b and average ionization fraction x{sub e} of the reionization processes, at z = 8 and the noise level of 60 mK we find that although the complex foreground can be well approximated with quadratic polynomial expansion, a significant part of the Mpc-scale components of the 21 cm signals (75% for {approx}> 6 h {sup -1} Mpc scales and 34% for {approx}> 1 h {sup -1} Mpc scales) is lost because it tends to be misidentified as part of the foreground when the single-narrow-segment separation approachmore » is applied. The best restoration of the 21 cm signals and the tightest determination of b and x{sub e} can be obtained with the three-narrow-segment fitting technique as proposed in this paper. Similar results can be obtained at other redshifts.« less

Authors:
; ; ; ;  [1]; ;  [2]; ; ;  [3]
  1. Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang, Shanghai 200240 (China)
  2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Nandan Road 80, Shanghai 200030 (China)
  3. National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100012 (China)
Publication Date:
OSTI Identifier:
22167142
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 763; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COMPARATIVE EVALUATIONS; COSMOLOGY; DATA ANALYSIS; HYDROGEN; POLYNOMIALS; RED SHIFT; SIGNALS; SKY; SPECTRA; STARS; STATISTICS; TOMOGRAPHY; UNIVERSE

Citation Formats

Wang, Jingying, Xu, Haiguang, Guo, Xueying, Li, Weitian, Liu, Chengze, An, Tao, Wang, Yu, Gu, Junhua, Martineau-Huynh, Olivier, and Wu, Xiang-Ping, E-mail: hgxu@sjtu.edu.cn, E-mail: zishi@sjtu.edu.cn. EXPLORING THE COSMIC REIONIZATION EPOCH IN FREQUENCY SPACE: AN IMPROVED APPROACH TO REMOVE THE FOREGROUND IN 21 cm TOMOGRAPHY. United States: N. p., 2013. Web. doi:10.1088/0004-637X/763/2/90.
Wang, Jingying, Xu, Haiguang, Guo, Xueying, Li, Weitian, Liu, Chengze, An, Tao, Wang, Yu, Gu, Junhua, Martineau-Huynh, Olivier, & Wu, Xiang-Ping, E-mail: hgxu@sjtu.edu.cn, E-mail: zishi@sjtu.edu.cn. EXPLORING THE COSMIC REIONIZATION EPOCH IN FREQUENCY SPACE: AN IMPROVED APPROACH TO REMOVE THE FOREGROUND IN 21 cm TOMOGRAPHY. United States. doi:10.1088/0004-637X/763/2/90.
Wang, Jingying, Xu, Haiguang, Guo, Xueying, Li, Weitian, Liu, Chengze, An, Tao, Wang, Yu, Gu, Junhua, Martineau-Huynh, Olivier, and Wu, Xiang-Ping, E-mail: hgxu@sjtu.edu.cn, E-mail: zishi@sjtu.edu.cn. Fri . "EXPLORING THE COSMIC REIONIZATION EPOCH IN FREQUENCY SPACE: AN IMPROVED APPROACH TO REMOVE THE FOREGROUND IN 21 cm TOMOGRAPHY". United States. doi:10.1088/0004-637X/763/2/90.
@article{osti_22167142,
title = {EXPLORING THE COSMIC REIONIZATION EPOCH IN FREQUENCY SPACE: AN IMPROVED APPROACH TO REMOVE THE FOREGROUND IN 21 cm TOMOGRAPHY},
author = {Wang, Jingying and Xu, Haiguang and Guo, Xueying and Li, Weitian and Liu, Chengze and An, Tao and Wang, Yu and Gu, Junhua and Martineau-Huynh, Olivier and Wu, Xiang-Ping, E-mail: hgxu@sjtu.edu.cn, E-mail: zishi@sjtu.edu.cn},
abstractNote = {With the intent of correctly restoring the redshifted 21 cm signals emitted by neutral hydrogen during the cosmic reionization processes, we re-examine the separation approaches based on the quadratic polynomial fitting technique in frequency space in order to investigate whether they work satisfactorily with complex foreground by quantitatively evaluating the quality of restored 21 cm signals in terms of sample statistics. We construct the foreground model to characterize both spatial and spectral substructures of the real sky, and use it to simulate the observed radio spectra. By comparing between different separation approaches through statistical analysis of restored 21 cm spectra and corresponding power spectra, as well as their constraints on the mean halo bias b and average ionization fraction x{sub e} of the reionization processes, at z = 8 and the noise level of 60 mK we find that although the complex foreground can be well approximated with quadratic polynomial expansion, a significant part of the Mpc-scale components of the 21 cm signals (75% for {approx}> 6 h {sup -1} Mpc scales and 34% for {approx}> 1 h {sup -1} Mpc scales) is lost because it tends to be misidentified as part of the foreground when the single-narrow-segment separation approach is applied. The best restoration of the 21 cm signals and the tightest determination of b and x{sub e} can be obtained with the three-narrow-segment fitting technique as proposed in this paper. Similar results can be obtained at other redshifts.},
doi = {10.1088/0004-637X/763/2/90},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 763,
place = {United States},
year = {2013},
month = {2}
}