Refined study of isocurvature fluctuations in the curvaton scenario

Naoya Kitajima, David Langlois, Tomo Takahashi, Shuichiro Yokoyama

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4 Citations (Scopus)


We revisit the generation of dark matter isocurvature perturbations in the curvaton model in greater detail, both analytically and numerically. As concrete examples, we investigate the cases of thermally decoupled dark matter and axionic dark matter. We show that the radiation produced by the decay of the curvaton, which has not been taken into account in previous analytical studies, can significantly affect the amplitude of isocurvature perturbations. In particular, we find that they are drastically suppressed even when the dark matter freeze-out (or the onset of the axion oscillations for axionic dark matter) occurs before the curvaton decays, provided the freeze-out takes place deep in the curvaton-dominated Universe. As a consequence, we show that the current observational isocurvature constraints on the curvaton parameters are not as severe as usually thought.

Original languageEnglish
Article number042
JournalJournal of Cosmology and Astroparticle Physics
Issue number12
Publication statusPublished - 2017 Dec 27


  • Cosmological perturbation theory
  • Inflation
  • Physics of the early universe


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