Abstract

We present new constraints on parameters of cosmic dawn and the epoch of reionization derived from the EDGES High-Band spectrum (90-190 MHz). The parameters are probed by evaluating global 21 cm signals generated with the recently developed Global21cm tool. This tool uses neural networks trained and tested on similar to 30,000 spectra produced with semi-numerical simulations that assume the standard thermal evolution of the cosmic microwave background and the intergalactic medium. From our analysis, we constrain at 68% (1) the minimum virial circular velocity of star-forming halos to V-c < 19.3 km s(-1), (2) the X-ray heating efficiency of early sources to f(x) > 0.0042, and (3) the low-energy cutoff of the X-ray spectral energy distribution to nu(min) < 2.3 keV. We also constrain the star formation efficiency (f(*)), the electron scattering optical depth (tau(e)), and the mean-free path of ionizing photons (R-mfp). We recompute the constraints after incorporating into the analysis four estimates for the neutral hydrogen fraction from high-z quasars and galaxies, and a prior on tau(e) from Planck 2018. The largest impact of the external observations is on the parameters that most directly characterize reionization. Specifically, we derive the combined 68% constraints tau(e) < 0.063 and R-mfp > 27.5 Mpc. The external observations also have a significant effect on V-c due to its degeneracy with tau(e), while the constraints on f(*),f(x), and nu(min), remain primarily determined by EDGES.