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Roy, I., Xu, W., Qiu, J., Shu, C. and Fang, L. (2009) Wouthuysen-Field Coupling in the 21 cm Region around High-Redshift Sources. The Astrophysical Journal, 703, 1992-2003.
https://doi.org/10.1088/0004-637x/703/2/1992

has been cited by the following article:

• TITLE: How Cloud-9 Observations Could Be Consistent with the Cold Hydogen Dark Matter (CHDM) Theory (a Brief Note)

  AUTHORS: Eugene Terry Tatum

  KEYWORDS: Cloud-9, Dark Matter, Cold Hydrogen Dark Matter, CHDM, Cosmic Dawn, Circumgalactic Medium, RELHIC, Wouthuysen-Field Effect

  JOURNAL NAME: Journal of Modern Physics, Vol.17 No.2, February 14, 2026

  ABSTRACT: It is suggested that the CHDM theory can be seamlessly integrated into the ΛCDM model and cosmological timeline, including a likely explanation of Cosmic Dawn and “Cloud-9” observations. Confirmatory evidence necessary for acceptance of the CHDM theory may lie in further study of the Cloud-9 dark matter halo or the halo of another RELHIC gas cloud, as described herein. For example, the discovery of an unusually strong 21-cm absorption line within a quasar spectrum in the background of a RELHIC would provide strong evidentiary support for CHDM. Counterarguments to the CHDM theory which focus on “missing” hydrogen baryonic matter appear to be refuted by comparing the Posti & Helmi 20 kpc radius Milky Way halo dark matter mass (635 billion solar masses) to a high-end estimate of the deep space cold neutral hydrogen mass (827 billion solar masses) within the same halo.