Detecting the Earliest Galaxies through Two New Sources of 21 Centimeter Fluctuations

  title={Detecting the Earliest Galaxies through Two New Sources of 21 Centimeter Fluctuations},
  author={Rennan Barkana and Abraham Loeb},
  journal={The Astrophysical Journal},
The first galaxies that formed at a redshift z ~ 20-30 emitted continuum photons with energies between the Lyα and Lyman limit wavelengths of hydrogen, to which the neutral universe was transparent except at the Lyman series resonances. As these photons redshifted or scattered into the Lyα resonance, they coupled the spin temperature of the 21 cm transition of hydrogen to the gas temperature, allowing it to deviate from the microwave background temperature. We show that the fluctuations in the… 

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