Testing for calibration systematics in the EDGES low-band data using Bayesian model selection

Understand

Cosmic Dawn, when the first stars and proto-galaxies began to form, is commonly expected to be accompanied by an absorption signature at radio frequencies.

• This feature arises as Lyman-$\alpha$ photons emitted by these first luminous objects couple the 21 cm excitation temperature of intergalactic hydrogen gas to its kinetic temperature, driving it into absorption relative to the CMB.
• The detailed properties of this absorption profile encode powerful information about the physics of Cosmic Dawn.
• Recently, Bowman et al.