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Cosmic microwave background power asymmetry from primordial sound speed parameter

Yi-Fu Cai1, Wen Zhao2, and Yang Zhang2

  • 1Department of Physics, McGill University, Montréal, Quebec H3A 2T8, Canada
  • 2Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026, China

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Phys. Rev. D 89, 023005 – Published 16 January, 2014

DOI: https://doi.org/10.1103/PhysRevD.89.023005

Abstract

The hemispherical power asymmetry in the cosmic microwave background can be explained by the modulation of some primordial cosmological parameters, such as the sound speed of the inflaton. Inspired by new physics beyond the standard knowledge of particle cosmology, this sound speed modulation greatly enriches the cosmological perturbation theory. We numerically examine the mechanism of the sound speed modulation and show it can be nicely consistent with current observations. Furthermore, this mechanism predicts that power asymmetry also exists in the temperature-polarization correlation and polarization autocorrelation of the cosmic microwave background with the same shape and in primordial non-Gaussianity of equilateral type with a particular shape. Therefore, our mechanism is observationally detectable in the forthcoming experiments.

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Phys. Rev. D 89, 023005– Published 16 January, 2014
  • Received 24 July 2013

© 2014 American Physical Society

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