https://doi.org/10.1140/epjc/s10052-021-09029-4
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
Received:
14
December
2020
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
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