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21-cm fluctuations from inhomogeneous X-ray heating before reionization

Pritchard, Jonathan R. and Furlanetto, Steven R. (2007) 21-cm fluctuations from inhomogeneous X-ray heating before reionization. Monthly Notices of the Royal Astronomical Society, 376 (4). pp. 1680-1694. ISSN 0035-8711. doi:10.1111/j.1365-2966.2007.11519.x.

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Many models of early structure formation predict a period of heating immediately preceding reionization, when X-rays raise the gas temperature above that of the cosmic microwave background. These X-rays are often assumed to heat the intergalactic medium (IGM) uniformly, but in reality will heat the gas more strongly closer to the sources. We develop a framework for calculating fluctuations in the 21-cm brightness temperature that originate from this spatial variation in the heating rate. High-redshift sources are highly clustered, leading to significant gas temperature fluctuations (with fractional variations ∼40 per cent, peaking on k∼0.1 Mpc^−1 scales). This induces a distinctive peak-trough structure in the angle-averaged 21-cm power spectrum, which may be accessible to the proposed Square Kilometre Array. This signal reaches the ∼10 mK level, and is stronger than that induced by Lyα flux fluctuations. As well as probing the thermal evolution of the IGM before reionization, this 21-cm signal contains information about the spectra of the first X-ray sources. Finally, we consider disentangling temperature, density and Lyα flux fluctuations as functions of redshift.

Item Type:Article
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Furlanetto, Steven R.0000-0002-0658-1243
Additional Information:© 2007 The Authors. Journal compilation © 2007 RAS. Accepted 2007 January 16. Received 2006 December 14; in original form 2006 July 11. Published Online: 26 March 2007. This work was supported at Caltech in part by DoE DE-FG03-92-ER40701. JRP would like to thank Miguel Morales for useful discussions. SRF thanks the Tapir group at Caltech for hospitality while this work was completed. We would also like to thank the anonymous referee for many useful comments that have helped improve the clarity of the paper.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG03-92-ER40701
Subject Keywords:intergalactic medium • cosmology: theory • diffuse radiation • X-rays: diffuse background
Issue or Number:4
Record Number:CaltechAUTHORS:PRImnras07b
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12974
Deposited By: Archive Administrator
Deposited On:13 Jan 2009 01:03
Last Modified:08 Nov 2021 22:34

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