Statistical anisotropies in temperature and polarization fluctuations from a scaledependent trispectrum
Abstract
We study statistical anisotropies generated in the observed twopoint function of the cosmic microwave background (CMB) fluctuations if the primordial statistics are nonGaussian. Focusing on the dipole modulations of the anisotropies, we find that the hemispherical power asymmetry observed in the CMB temperature fluctuations can be modeled by a localtype trispectrum with amplitude τ_{NL}(k_{p}=0.05 Mpc^{1})≈2 ×10^{4} and a large red tilt n ≈0.68 . We numerically evaluate the nonGaussian covariance of the modulation estimators for both temperature and Emode polarization fluctuations and discuss the prospects of constraining the model using Planck satellite data. We then discuss other effects of the scaledependent trispectrum that could be used to distinguish this scenario from other explanations of the power asymmetry: higherorder modulations of the twopoint function and the nonGaussian angular power spectrum covariance. As an important consequence of the nonGaussian power spectrum covariance, we discuss how the CMBinferred spectral index of primordial scalar fluctuations can be significantly biased in the presence of a scaledependent localtype trispectrum.
 Publication:

Physical Review D
 Pub Date:
 July 2018
 DOI:
 10.1103/PhysRevD.98.023520
 arXiv:
 arXiv:1805.00037
 Bibcode:
 2018PhRvD..98b3520A
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 11 pages, 4 figures