Spectator field models in light of spectral index after Planck

Takeshi Kobayashi, Fuminobu Takahashi, Tomo Takahashi, Masahide Yamaguchi

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


We revisit spectator field models including curvaton and modulated reheating scenarios, specifically focusing on their viability in the new Planck era, based on the derived expression for the spectral index in general spectator field models. Importantly, the recent Planck observations give strong preference to a red-tilted power spectrum, while the spectator field models tend to predict a scale-invariant one. This implies that, during inflation, either (i) the Hubble parameter varies significantly as in chaotic inflation, or (ii) a scalar potential for the spectator field has a relatively large negative curvature. Combined with the tight constraint on the non-Gaussianity, the Planck data provides us with rich implications for various spectator field models.

Original languageEnglish
Article number042
JournalJournal of Cosmology and Astroparticle Physics
Issue number10
Publication statusPublished - 2013 Oct


  • cosmological parameters from CMBR
  • inflation
  • physics of the early universe
  • power spectrum

ASJC Scopus subject areas

  • Astronomy and Astrophysics


Dive into the research topics of 'Spectator field models in light of spectral index after Planck'. Together they form a unique fingerprint.

Cite this