# The Wouthuysen‐Field effect in a clumpy intergalactic medium

@article{Higgins2009TheWE,
title={The Wouthuysen‐Field effect in a clumpy intergalactic medium},
author={Jonathan Higgins and Avery Meiksin},
journal={Monthly Notices of the Royal Astronomical Society},
year={2009},
volume={393},
pages={949-958}
}
• Published 7 November 2008
• Physics
• Monthly Notices of the Royal Astronomical Society
We show that the high optical depth of the intergalactic medium to Lya photons before the Epoch of Re-ionization results in a negligible magnitude for the Wouthuysen-Field effect produced by a radiation source on its distant surroundings, unless (i) the scattering medium has sufficient time for the impinging resonance line photons to establish a steady-state frequency distribution or (ii) the scattering gas is undergoing internal expansion or has a peculiar motion of tens to hundreds of km s -1…
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