EDGES result versus CMB and low-redshift constraints on ionization histories

Abstract

We examine the results from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES), which has recently claimed the detection of a strong absorption in the 21 cm hyperfine transition line of neutral hydrogen, at redshifts demarcating the early stages of star formation. More concretely, we study the compatibility of the shape of the EDGES absorption profile, centered at a redshift of $z\sim 17.2$, with measurements of the reionization optical depth, the Gunn-Peterson optical depth, and Lyman-$\alpha$ emission from star-forming galaxies, for a variety of possible reionization models within the standard $\Lambda$CDM framework (that is, a Universe with a cosmological constant and cold dark matter). When, conservatively, we only try to accommodate the location of the absorption dip, we identify a region in the parameter space of the astrophysical parameters that successfully explains all of the aforementioned observations. However, one of the most abnormal features of the EDGES measurement is the absorption amplitude, which is roughly a factor of two larger than the maximum allowed value in the $\Lambda$CDM framework. We point out that the simple considered astrophysical models that produce the largest absorption amplitudes are unable to explain the depth of the dip and of reproducing the observed shape of the absorption profile.

v2: Published version, citations added and minor modifications to text. v1: 8 pages, 4 figures

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Cited by in corpus (14)

• Neutrino Mass Ordering from Oscillations and Beyond: 2018 Status and Future Prospects
• The redshifted 21-cm signal in the EDGES low-band spectrum
• Constraining the primordial black hole abundance with 21cm cosmology
• Dawn of the dark: unified dark sectors and the EDGES Cosmic Dawn 21-cm signal
• The Implications of a Pre-reionization 21 cm Absorption Signal for Fuzzy Dark Matter
• Dark Photon Dark Matter in the Presence of Inhomogeneous Structure
• Dark Matter microphysics and 21 cm observations
• Removing Astrophysics in 21 cm maps with Neural Networks
• Constraints on ALPs and excited dark matter from the EDGES 21-cm absorption signal
• Global radiation signature from early structure formation
• Impact of EDGES 21cm Global Signal on Primordial Power Spectrum
• Variations in fundamental constants at the cosmic dawn
• Predictions for the sky-averaged depth of the 21cm absorption signal at high redshift in cosmologies with and without non-baryonic cold dark matter
• Astrophysical uncertainties challenge 21-cm forecasts: A primordial black hole case study