Cosmological baryon sound waves coupled with the primeval radiation

Kazuhiro Yamamoto, Naoshi Sugiyama, Humitaka Sato

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


The fluid equations for the baryon-electron system in an expanding universe are derived from the Boltzmann equation. The effect of the Compton interaction is taken into account properly in order to evaluate the photon-electron collisional term. As an application, the acoustic motions of the baryon-electron system after recombination are investigated. The effective adiabatic index [Formula presented] is computed for sound waves of various wavelengths, assuming the perturbation amplitude is small. The oscillations are found to be dumped when [Formula presented] changes from between 1 (for an isothermal process) to 5/3 (for an adiabatic process).

Original languageEnglish
Pages (from-to)7566-7577
Number of pages12
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number12
Publication statusPublished - 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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