Regular Article – Theoretical Physics
The anomalous 21-cm absorption at high redshifts
Department of Physics, The Applied Math Program, and Department of Astronomy, The University of Arizona, 85721, Tucson, AZ, USA
Accepted: 6 March 2021
Published online: 15 March 2021
The EDGES collaboration has reported the detection of a global 21-cm signal with a plateau centered at 76 MHz (i.e., redshift 17.2), with an amplitude of mK. This anomalous measurement does not comport with standard cosmology, which can only accommodate an amplitude mK. Nevertheless, the line profile’s redshift range () suggests a possible link to Pop III star formation and an implied evolution out of the ‘dark ages.’ Given this tension with the standard model, we here examine whether the observed 21-cm signal is instead consistent with the results of recent modeling based on the alternative Friedmann–Lemaître–Robertson–Walker cosmology known as the universe, showing that – in this model – the CMB radiation might have been rethermalized by dust ejected into the IGM by the first-generation stars at redshift . We find that the requirements for this process to have occurred would have self-consistently established an equilibrium spin temperature K in the neutral hydrogen, via the irradiation of the IGM by deep penetrating X-rays emitted at the termination shocks of Pop III supernova remnants. Such a dust scenario has been strongly ruled out for the standard model, so the spin temperature ( K) inferred from the 21-cm absorption feature appears to be much more consistent with the profile than that implied by CDM, for which adiabatic cooling would have established a spin temperature K.
© The Author(s) 2021
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3