21 cm radiation - a new probe of variation in the fine structure constant

Abstract

We investigate the effect of variation in the value of the fine structure constant at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in the fine structure constant and it is so far the only probe of the fine structure constant in this redshift range. A change in the value of the fine structure constant by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by > 5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by ~ 5%.

5 pages, 5 figures, published version + extra figures

References in corpus (3)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The CMBR fluctuations from HI perturbations prior to reionization
• CMB constraints on the fine structure constant

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• Time variation of the fine structure constant in the early universe and the Bekenstein model
• Nonlinear electrodynamics and the variation of the fine structure constant
• Constraining runaway dilaton models using joint gravitational-wave and electromagnetic observations