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Authors: R. Monsalve, B. Greig, J. Bowman, A. Mesinger, A. Rogers, T. Mozdzen, N. Kern, N. Mahesh

Abstract: We use the sky-average spectrum measured by EDGES High-Band (90−190 MHz) to constrain parameters of early galaxies independent of the absorption feature at 78~MHz reported by Bowman et al. (2018). These parameters represent traditional models of cosmic dawn and the epoch of reionization produced with the 21cmFAST simulation code (Mesinger & Furlanetto 2007, Mesinger et al. 2011). The parameters considered are: (1) the UV ionizing efficiency (ζ), (2) minimum halo virial temperature hosting efficient star-forming galaxies (Tminvir), (3) integrated soft-band X-ray luminosity (LX<2keV/SFR), and (4) minimum X-ray energy escaping the first galaxies (E0), corresponding to a typical HI column density for attenuation through the interstellar medium. The High-Band spectrum disfavors high values of Tminvir and ζ, which correspond to signals with late absorption troughs and sharp reionization transitions. It also disfavors intermediate values of LX<2keV/SFR, which produce relatively deep and narrow troughs within the band.