Allowing for enhanced Lyα photon line emission from Population III dominated stellar systems in the first forming galaxies, we show the 21-cm cosmic dawn signal at 10 < z < 30 may substantially differ from standard scenarios. Energy transfer by Lyα photons emerging from galaxies may heat intergalactic gas if H ii regions within galaxies are recombination bound, or cool the gas faster than by adiabatic expansion if reddened by winds internal to the haloes. In some extreme cases, differential 21-cm antenna temperatures near -500 mK may be achieved at 15 < z < 25, similar to the signature detected by the EDGES 21-cm cosmic dawn experiment.
Meiksin, A., Madau, P. (2021). The impact of Lyα emission line heating and cooling on the cosmic dawn 21-cm signal. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 501(2), 1920-1932 [10.1093/mnras/staa3830].
The impact of Lyα emission line heating and cooling on the cosmic dawn 21-cm signal
Madau P.
2021
Abstract
Allowing for enhanced Lyα photon line emission from Population III dominated stellar systems in the first forming galaxies, we show the 21-cm cosmic dawn signal at 10 < z < 30 may substantially differ from standard scenarios. Energy transfer by Lyα photons emerging from galaxies may heat intergalactic gas if H ii regions within galaxies are recombination bound, or cool the gas faster than by adiabatic expansion if reddened by winds internal to the haloes. In some extreme cases, differential 21-cm antenna temperatures near -500 mK may be achieved at 15 < z < 25, similar to the signature detected by the EDGES 21-cm cosmic dawn experiment.
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