Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB Polarization

TL;DR

This paper investigates how inhomogeneous and anisotropic primordial power spectra could explain the hemispherical anisotropy observed in CMB polarization, providing testable predictions to distinguish between models.

Contribution

It introduces inhomogeneous and anisotropic models of primordial power spectrum and derives their signatures in CMB polarization correlations, enabling observational tests.

Findings

Model parameters fit to TT correlations in CMB data.

Predicted correlations among multipoles for TE and EE modes.

Potential to distinguish between inhomogeneous and anisotropic models.

Abstract

We consider an inhomogeneous model and independently an anisotropic model of primordial power spectrum in order to describe the observed hemispherical anisotropy in Cosmic Microwave Background Radiation. This anisotropy can be parametrized in terms of the dipole modulation model of the temperature field. Both the models lead to correlations between spherical harmonic coefficients corresponding to multipoles, l and l \pm 1. We obtain the model parameters by making a fit to TT correlations in CMBR data. Using these parameters we predict the signature of our models for correlations among different multipoles for the case of the TE and EE modes. These predictions can be used to test whether the observed hemispherical anisotropy can be correctly described in terms of a primordial power spectrum. Furthermore these may also allow us to distinguish between an inhomogeneous and an anisotropic model.