Joint Consistency of the Optical Depth and the 21-cm Trough: Escape Fraction in the Bounce Frame
Year: 2026
Type: article
Abstract: Two constraints on the end of the cosmic dawn era are often used separately: the microwave-background optical depth, which integrates the ionisation history, and the absorption trough, which timestamps its beginning. Using the stated cosmology and the brightness-temperature relations described in the Methods, the calculation gives the following headline values: f esc = 0.16; f esc standard = 0.10; tau model = 0.058; tau planck = 0.054. The comparison values taken from the published record — including the EDGES and SARAS reports, HERA limits and the Planck optical depth where relevant — are used exactly as published, and the bounce contribution enters only through the named timing, heating or shear inputs. The result is a computed prediction for the delayed-onset history, with its sensitivity to each input stated in the Discussion. This study is simulated and computed from stated assumptions; it is not a measurement.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225785505
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