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Polarization of the Cosmic Microwave Background from Nonuniform Reionization

Liu, Guo-Chin and Sugiyama, Naoshi and Benson, Andrew J. and Lacey, C. G. and Nusser, Adi (2001) Polarization of the Cosmic Microwave Background from Nonuniform Reionization. Astrophysical Journal, 561 (2). pp. 504-516. ISSN 0004-637X. doi:10.1086/323255.

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We study the polarization anisotropy in the cosmic microwave background (CMB) resulting from patchy reionization of the intergalactic medium by stars in galaxies. It is well known that the polarization of the CMB is very sensitive to the details of reionization, including the reionization epoch and the density fluctuations in the ionized gas. We calculate the effects of reionization by combining a semianalytic model of galaxy formation, which predicts the redshifts and luminosities of the ionizing sources, with a high-resolution N-body simulation, to predict the spatial distribution of the ionized gas. The models predict reionization at redshifts z ~ 5-10, with electron scattering optical depths due to reionization of ~0.014-0.05. We find that reionization generates a peak in the polarization spectrum with amplitude ~0.05-0.15 μK at large angular scales (l ~ 3). The position of this peak reveals the size of the horizon at reionization, whilst its amplitude is a measure of the optical depth to reionization. On small scales (l ≳ 6000), reionization produces a second-order polarization signal due to the coupling of fluctuations in the free electron density with the quadrupole moment of the temperature anisotropy. Careful study reveals that this coupling generates equal second-order polarization power spectra for the electric and magnetic modes, with amplitude ~10 nK. This amplitude depends strongly on the total baryon density Ω_b and on the spatial correlations of the free electron density, and weakly on the fraction f_(esc) of ionizing photons able to escape their source galaxy. The first- and second-order signals are therefore sensitive to different details of how the reionization occurred. Detection of these signals will place important constraints on the reionization history of the universe.

Item Type:Article
Related URLs:
URLURL TypeDescription
Sugiyama, Naoshi0000-0003-4854-5387
Benson, Andrew J.0000-0001-5501-6008
Lacey, C. G.0000-0001-9016-5332
Nusser, Adi0000-0002-8272-4779
Alternate Title:Polarization of the Cosmic Microwave Background from Non-Uniform Reionization
Additional Information:© 2001. The American Astronomical Society. Received 2001 January 10; accepted 2001 July 11. We thank U. Seljak and M. Zaldarriaga for the use of CMBFAST; the Virgo Consortium for making available the GIF N-body simulations used here; and Shaun Cole, Carlos Frenk, and Carlton Baugh for allowing us to use their model of galaxy formation. G. C. L. thanks N. Seto for useful discussion and acknowledges the fellowship of Interchange Association. N. S., A. N., and C. G. L. acknowledge the kind hospitality of Carlos Frenk and the physics department of University of Durham during the TMR network meeting. N. S. is supported by the Sumitomo Foundation. C. G. L. acknowledges support at SISSA from COFIN funds from MURST and from ASI. A. N. and A. J. B. acknowledge the support of the EC RTN network "The Physics of the Intergalactic Medium." A. N. was supported by a grant from the Israeli Academy of Science.
Funding AgencyGrant Number
Interchange AssociationUNSPECIFIED
Sumitomo FoundationUNSPECIFIED
Ministero dell'Università e della Ricerca Scientifico-Tecnologica (MURST)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
European CommissionUNSPECIFIED
Israeli Academy of ScienceUNSPECIFIED
Subject Keywords:cosmic microwave background; cosmology: theory; galaxies: formation; intergalactic medium
Issue or Number:2
Record Number:CaltechAUTHORS:20170408-162545860
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Official Citation:Guo-Chin Liu et al 2001 ApJ 561 504
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76182
Deposited By: 1Science Import
Deposited On:09 Aug 2017 22:27
Last Modified:15 Nov 2021 16:58

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