The anomalous 21-cm absorption at high redshifts

Abstract The EDGES collaboration has reported the detection of a global 21-cm signal with plateau centered at 76 MHz (i.e., redshift 17.2), an amplitude $$500^{+200}_{-500}$$ 500 - + 200 mK. This anomalous measurement does not comport standard cosmology, which can only accommodate $$\lesssim 230$$ ≲ 230 Nevertheless, line profile’s range ( $$15\lesssim z\lesssim 20$$ 15 z 20 ) suggests possible link to Pop III star formation and implied evolution out ‘dark ages.’ Given this tension model, we here examine whether observed is instead consistent results recent modeling based on alternative Friedmann–Lemaître–Robertson–Walker cosmology known as $$R_{\mathrm{h}}=ct$$ R h = c t universe, showing that – in model CMB radiation might have been rethermalized by dust ejected into IGM first-generation stars $$z\sim 16$$ ∼ 16 . We find requirements for process occurred would self-consistently established equilibrium spin temperature $$T_{\mathrm{s}}\approx 3.4$$ T s ≈ 3.4 K neutral hydrogen, via irradiation deep penetrating X-rays emitted termination shocks supernova remnants. Such scenario strongly ruled so $$\sim 3.3$$ 3.3 K) inferred from absorption feature appears be much more profile than $$\Lambda $$ Λ CDM, adiabatic cooling $$T_\mathrm{s}(z=17.2)\sim 6$$ ( 17.2 ) 6 K.