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New probe of magnetic fields in the pre-reionization epoch. II. Detectability

Gluscevic, Vera and Venumadhav, Tejaswi and Fang, Xiao and Hirata, Christopher and Oklopčić, Antonija and Mishra, Abhilash (2017) New probe of magnetic fields in the pre-reionization epoch. II. Detectability. Physical Review D, 95 (8). Art. No. 083011. ISSN 2470-0010.

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In the first paper of this series, we proposed a novel method to probe large–scale intergalactic magnetic fields during the cosmic Dark Ages, using 21–cm tomography. This method relies on the effect of spin alignment of hydrogen atoms in a cosmological setting, and on the effect of magnetic precession of the atoms on the statistics of the 21-cm brightness-temperature fluctuations. In this paper, we forecast the sensitivity of future tomographic surveys to detecting magnetic fields using this method. For this purpose, we develop a minimum-variance estimator formalism to capture the characteristic anisotropy signal using the two-point statistics of the brightness-temperature fluctuations. We find that, depending on the reionization history, and subject to the control of systematics from foreground subtraction, an array of dipole antennas in a compact-grid configuration with a collecting area slightly exceeding one square kilometer can achieve a 1σ detection of ∼10^(−21)  Gauss comoving (scaled to present-day value) within three years of observation. Using this method, tomographic 21–cm surveys could thus probe ten orders of magnitude below current cosmic microwave background constraints on primordial magnetic fields, and provide exquisite sensitivity to large-scale magnetic fields in situ at high redshift.

Item Type:Article
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URLURL TypeDescription Paper
Venumadhav, Tejaswi0000-0002-1661-2138
Hirata, Christopher0000-0002-2951-4932
Oklopčić, Antonija0000-0002-9584-6476
Additional Information:© 2017 American Physical Society. Received 2 June 2016; published 21 April 2017. V. G. gratefully acknowledges the support from the W. M. Keck Foundation Fund at the Institute for Advanced Study. T. V. gratefully acknowledges support from the Schmidt Fellowship and the Fund for Memberships in Natural Sciences at the Institute for Advanced Study. X. F. is supported by the Simons Foundation and is grateful to Joseph McEwen for useful discussions. A. M., C. H., and A. O. are supported by the U.S. Department of Energy, the David & Lucile Packard Foundation, and the Simons Foundation. C. H. is supported by the National Aeronautics and Space Administration. The authors thank Juna Kollmeier and Francesco Haardt for useful conversations about the Lyman–α flux evolution, and Daniel Grin for useful comments on the manuscript. Illustrations in Fig. 2 made use of HEALPix [42] software package. The complete code implementing all the calculations presented in this work, along with the 21CMFAST reionization histories used as input, is available at
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Institute for Advanced StudyUNSPECIFIED
Simons FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20170421-135238268
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76823
Deposited By: Tony Diaz
Deposited On:21 Apr 2017 22:07
Last Modified:17 May 2017 22:46

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