Results from EDGES High-band. II. Constraints on Parameters of Early Galaxies

Raul A. Monsalve, Bradley Greig, Judd Bowman, Andrei Mesinger, Alan E.E. Rogers, Thomas J. Mozdzen, Nicholas S. Kern, Nivedita Mahesh

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32 Scopus citations


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. These parameters represent traditional models of cosmic dawn and the epoch of reionization produced with the 21cmFAST simulation code. The parameters considered are (1) the UV ionizing efficiency (ζ); (2) minimum halo virial temperature hosting efficient star-forming galaxies (Tvir min); (3) integrated soft-band X-ray luminosity (LX<2KeV/SFR); and (4) minimum X-ray energy escaping the first galaxies (E 0), corresponding to a typical H i column density for attenuation through the interstellar medium. The High-band spectrum disfavors high values Tvir min of 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. Specifically, we rule out 39.4 < log10( LX<2KeV/SFR) < 39.8 (95% C.L.). We then combine the EDGES High-band data with constraints on the electron-scattering optical depth from Planck and the hydrogen neutral fraction from high-z quasars. This produces a lower degeneracy between ζ and Tvir min than that reported by Greig & Mesinger using the Planck and quasar constraints alone. Our main result in this combined analysis is the estimate 4.5 ≤ log10 (Tvir min/K) ≤ 5.7(95% C.L.). We leave the evaluation of 21 cm models using simultaneously data from EDGES Low- and High-band for future work.

Original languageEnglish (US)
Article number11
JournalAstrophysical Journal
Issue number1
StatePublished - Aug 10 2018


  • cosmology: observations
  • early universe
  • galaxies: high-redshift
  • methods: data analysis

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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