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The anomalous 21-cm absorption at high redshifts
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The anomalous 21-cm absorption at high redshifts
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The anomalous 21-cm absorption at high redshifts
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Journal Article
The anomalous 21-cm absorption at high redshifts
2021
نظرة عامة
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
500
-
500
+
200
mK. This anomalous measurement does not comport with standard cosmology, which can only accommodate an amplitude
≲
230
mK. Nevertheless, the line profile’s redshift range (
15
≲
z
≲
20
) 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
R
h
=
c
t
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
z
∼
16
. We find that the requirements for this process to have occurred would have self-consistently established an equilibrium spin temperature
T
s
≈
3.4
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 (
∼
3.3
K) inferred from the 21-cm absorption feature appears to be much more consistent with the
R
h
=
c
t
profile than that implied by
Λ
CDM, for which adiabatic cooling would have established a spin temperature
T
s
(
z
=
17.2
)
∼
6
K.
الناشر
Springer Berlin Heidelberg,Springer,Springer Nature B.V,SpringerOpen
