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Paper   IPM / Astronomy / 14277
School of Astronomy
  Title:   Microwave Background Correlations from Dipole Anisotropy Modulation
1.  S. Aiola
2.  B. Wang
3.  A. Kosowsky
4.  T. Kahniashvili
5.  H. Firouzjahi
  Status:   Published
  Journal: Phys. Rev. D
  Year:  2015
  Supported by:            ipm IPM
Full-sky maps of the cosmic microwave background temperature reveal a 7% asymmetry of uctuation power between two halves of the sky. A common phenomenological model for this asymmetry is an overall dipole modulation of statistically isotropic uctuations, which produces particular o-diagonal correlations between multipole coecients. We compute these correlations and constructcorresponding estimators for the amplitude and direction of the dipole modulation. Applying these estimators to various cut-sky temperature maps from Planck and WMAP data shows consistency with a dipole modulation, diering from a null signal at 2.5 , with an amplitude and direction con- sistent with previous ts based on the temperature uctuation power. The signal is scale dependent, with a statistically signicant amplitude at angular scales larger than 2 degrees. Future measure- ments of microwave background polarization and gravitational lensing can increase the signicance of the signal. If the signal is not a statistical uke in an isotropic Universe, it requires new physics beyond the standard model of cosmology.

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