Direction dependence of the power spectrum and its effect on the Cosmic Microwave Background Radiation

Abstract

We study several anisotropic inflationary models and their implications for the observed violation of statistical isotropy in the CMBR data. In two of these models the anisotropy decays very quickly during the inflationary phase of expansion. We explicitly show that these models lead to violation of isotropy only for low l CMBR modes. Our primary aim is to fit the observed alignment of l=2,3 multipoles to the theoretical models. We use two measures, based on the power tensor, which contains information about the alignment of each multipole, to quantify the anisotropy in data. One of the measures uses the dispersion in eigenvalues of the power tensor. We also define another measure which tests the overall correlation between two different multipoles. We perturbatively compute these measures of anisotropy and fix the theoretical parameters by making a best fit to l=2,3 multipoles. We show that some of the models studied are able to consistently explain the observed violation of statistical isotropy.

19 pages, 1 figure

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Cited by in corpus (22)

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• Quadrupole--octopole alignment of CMB related to primordial power spectrum with dipolar modulation in anisotropic spacetime
• Testing the Dipole Modulation Model in CMBR
• Probing statistical isotropy of cosmological radio sources using SKA
• North-South non-Gaussian asymmetry in PLANCK CMB maps
• Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy
• Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB Polarization
• Clustering of Local Extrema in Planck CMB maps
• Superhorizon perturbations: A possible explanation of the Hubble--Lemaître Tension and the Large Scale Anisotropy of the Universe
• Explaining Excess Dipole in NVSS Data Using Superhorizon Perturbation
• Testing statistical Isotropy in Cosmic Microwave Background Polarization maps
• Noncommutative Geometry and the Primordial Dipolar Imaginary Power Spectrum
• A study of Dipolar Signal in distant Quasars with various observables
• A Pixel Space Method for Testing Dipole Modulation in the CMB Polarization
• Cosmological Power Spectrum in Non-commutative Space-time
• Anisotropic power spectrum and the observed low-l power in PLANCK CMB data
• Probing Cosmology beyond $\Lambda$CDM using the SKA
• Matter Dipole and Hubble Tension due to Large Wavelength Perturbations
• CMB Polarization by the Asymmetric Template of Scalar Perturbations