Footprints of statistical anisotropies

C. Armendariz-Picon

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We propose and develop a formalism to describe and constrain statistically anisotropic primordial perturbations. Starting from a decomposition of the primordial power spectrum in spherical harmonics, we find how the temperature fluctuations observed in the CMB sky are directly related to the coefficients in this harmonic expansion. Although the angular power spectrum does not discriminate between statistically isotropic and anisotropic perturbations, it is possible to define analogous quadratic estimators that are direct measures of statistical anisotropy. As a simple illustration of our formalism we test for the existence of a preferred direction in the primordial perturbations using full-sky CMB maps. We do not find significant evidence supporting the existence of a dipole component in the primordial spectrum.

Original languageEnglish (US)
Article number002
JournalJournal of Cosmology and Astroparticle Physics
Issue number3
StatePublished - Mar 1 2006


  • CMBR theory
  • Cosmological perturbation theory

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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