Concerns about Modelling of the EDGES Data

Abstract

It is predicted that the spectrum of radio emission from the whole sky should show a dip arising from the action of the light from the first stars on the hydrogen atoms in the surrounding gas, which causes the 21-cm line to appear in absorption against the cosmic microwave background. Bowman et al. 2018 identified a broad flat-bottomed absorption profile centred at 78 MHz, which could be this feature, although the depth of the profile is much larger than expected. We have examined the modelling process they used and find that their data implies unphysical parameters for the foreground emission and also that their solution is not unique in the sense that we found other simple formulations for the signal that are different in shape but that also fit their data. We argue that this calls into question the interpretation of these data as an unambiguous detection of the cosmological 21-cm absorption signature.

arXiv comment6 pages, 2 figures; Accepted version of article published December 19, 2018. Full edited version (incl. supplementary information) available through Springer Nature at https://doi.org/10.1038/s41586-018-0796-5

References in corpus (9)

• An absorption profile centred at 78 megahertz in the sky-averaged spectrum
• 21-cm cosmology
• PolyChord: nested sampling for cosmology
• PolyChord: next-generation nested sampling
• A model of diffuse Galactic Radio Emission from 10 MHz to 100 GHz
• An Improved Model of Diffuse Galactic Radio Emission from 10 MHz to 5 THz
• Foreground Model and Antenna Calibration Errors in the Measurement of the Sky-Averaged λ21 cm Signal at z~20
• Improved Measurement of the Spectral Index of the Diffuse Radio Background Between 90 and 190 MHz
• Radiometric Measurements of Electron Temperature and Opacity of Ionospheric Perturbations

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