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The impact of spin-temperature fluctuations on the 21-cm moments

Publication available at: https://arxiv.org/pdf/1505.07108.pdf
Title: The impact of spin-temperature fluctuations on the 21-cm moments
Authors: Watkinson, CA
Pritchard, JR
Item Type: Journal Article
Abstract: This paper considers the impact of Lyman α coupling and X-ray heating on the 21-cm brightness-temperature one-point statistics (as predicted by seminumerical simulations). The X-ray production efficiency is varied over four orders of magnitude and the hardness of the X-ray spectrum is varied from that predicted for high-mass X-ray binaries, to the softer spectrum expected from the hot interstellar medium. We find peaks in the redshift evolution of both the variance and skewness associated with the efficiency of X-ray production. The amplitude of the variance is also sensitive to the hardness of the X-ray spectral energy distribution. We find that the relative timing of the coupling and heating phases can be inferred from the redshift extent of a plateau that connects a peak in the variance's evolution associated with Lyman α coupling to the heating peak. Importantly, we find that late X-ray heating would seriously hamper our ability to constrain reionization with the variance. Late X-ray heating also qualitatively alters the evolution of the skewness, providing a clean way to constrain such models. If foregrounds can be removed, we find that LOFAR, MWA and PAPER could constrain reionization and late X-ray heating models with the variance. We find that HERA and SKA (phase 1) will be able to constrain both reionization and heating by measuring the variance using foreground-avoidance techniques. If foregrounds can be removed they will also be able to constrain the nature of Lyman α coupling.
Issue Date: 2-Oct-2015
Date of Acceptance: 27-Aug-2015
URI: http://hdl.handle.net/10044/1/51999
DOI: https://dx.doi.org/10.1093/mnras/stv2010
ISSN: 0035-8711
Publisher: Oxford University Press (OUP)
Start Page: 1416
End Page: 1431
Journal / Book Title: Monthly Notices of the Royal Astronomical Society
Volume: 454
Issue: 2
Copyright Statement: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Sponsor/Funder: Imperial College Trust
Science and Technology Facilities Council (STFC)
Commission of the European Communities
Science and Technology Facilities Council [2006-2012]
Funder's Grant Number: N/A
ST/K001051/1
321933
ST/K001051/1
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
methods: statistical
intergalactic medium
cosmology: theory
dark ages, reionization, first stars
21 CM SIGNAL
STAR-FORMING GALAXIES
X-RAY-EMISSION
H II REGIONS
COSMIC REIONIZATION
INTERGALACTIC MEDIUM
POWER SPECTRUM
HIGH-REDSHIFT
1ST STARS
CENTIMETER TOMOGRAPHY
0201 Astronomical And Space Sciences
Publication Status: Published
Open Access location: https://arxiv.org/pdf/1505.07108.pdf
Appears in Collections:Physics
Astrophysics



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