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

  title={21-cm radiation: a new probe of variation in the fine-structure constant.},
  author={Rishi Khatri and Benjamin D. Wandelt},
  journal={Physical review letters},
  volume={98 11},
We investigate the effect of variation in the value of the fine-structure constant (alpha) 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 alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature… Expand

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