Probing the epoch of early baryonic infall through 21-cm fluctuations

R. Barkana, A. Loeb

Research output: Contribution to journalLetterpeer-review


After cosmological recombination, the primordial hydrogen gas decoupled from the cosmic microwave background (CMB) and fell into the gravitational potential wells of the dark matter. The neutral hydrogen imprinted acoustic oscillations on the pattern of brightness fluctuations due to its redshifted 21-cm absorption of the CMB. Unlike CMB temperature fluctuations which probe the power spectrum at cosmic recombination, we show that observations of the 21-cm fluctuations at z ~ 20-200 can measure four separate fluctuation modes (with a fifth mode requiring very high precision), thus providing a unique probe of the geometry and composition of the universe.

Original languageEnglish
Pages (from-to)L36-L40
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Oct 2005


  • Cosmology: theory
  • Galaxies: formation
  • Galaxies: high-redshift


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