The impact of Lyman-$\alpha$ emission line heating and cooling on the cosmic dawn 21-cm signal

Abstract

Allowing for enhanced Ly$\alpha$ 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 Ly$\alpha$ photons emerging from galaxies may heat intergalactic gas if HII 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 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.

13 pages, 8 figures, submitted to MNRAS 31 May 2020

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Cited by in corpus (8)

• The subtlety of Ly-a photons: changing the expected range of the 21-cm signal
• Introducing SPHINX-MHD: The Impact of Primordial Magnetic Fields on the First Galaxies, Reionization, and the Global 21cm Signal
• Lyman-$\alpha$ coupling and heating at Cosmic Dawn
• Black holes at cosmic dawn in the redshifted 21cm signal of HI
• Constraining the Hubble parameter with the 21 cm brightness temperature signal in a universe with inhomogeneities
• 21 cm Signal from the Thermal Evolution of Lyman-$\alpha$ during Cosmic Dawn
• Thermal Evolution of the IGM due to Lyman-α photons during the Cosmic Dawn
• Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys