Axion cosmology and the energy scale of inflation

Mark P. Hertzberg, Max Tegmark, Frank Wilczek

Research output: Contribution to journalArticlepeer-review

209 Scopus citations


We survey observational constraints on the parameter space of inflation and axions and map out two allowed windows: the classic window and the inflationary anthropic window. The cosmology of the latter is particularly interesting; inflationary axion cosmology predicts the existence of isocurvature fluctuations in the cosmic microwave background, with an amplitude that grows with both the energy scale of inflation and the fraction of dark matter in axions. Statistical arguments favor a substantial value for the latter, and so current bounds on isocurvature fluctuations imply tight constraints on inflation. For example, an axion Peccei-Quinn scale of 1016GeV excludes any inflation model with energy scale >3.8×1014GeV (r>2×10-9) at 95% confidence, and so implies negligible gravitational waves from inflation, but suggests appreciable isocurvature fluctuations.

Original languageEnglish (US)
Article number083507
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number8
StatePublished - Oct 3 2008
Externally publishedYes

ASJC Scopus subject areas

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


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