Quantum noise and large-scale cosmic microwave background anisotropy

Chun Hsien Wu*, Kin Wang Ng, Wolung Lee, Da Shin Lee, Yeo Yie Charng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


We propose a new source for the cosmological density perturbation which is passive fluctuations of the inflaton driven dynamically by a coloured quantum noise as a result of its coupling to other massive quantum fields. The created fluctuations grow with time during inflation before horizon-crossing. However, the larger-scale modes cross the horizon earlier, thus resulting in a suppression of their density perturbation as compared with those on small scales. By using current observed CMB data to constrain the parameters introduced, we find that a significant contribution from the noise-driven perturbation to the density perturbation is still allowed. It in turn gives rise to a suppression of the large-scale CMB anisotropy that may be relevant to the observed low quadrupole in the WMAP CMB anisotropy data. We also briefly discuss the implications to the energy scale of inflation and the spectral index and the non-Gaussianity of the density perturbation.

Original languageEnglish
Article number006
JournalJournal of Cosmology and Astroparticle Physics
Issue number2
Publication statusPublished - 2007 Feb 1


  • CMBR theory
  • Inflation
  • Physics of the early universe
  • Power spectrum

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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