Testing statistical Isotropy in Cosmic Microwave Background Polarization maps

TL;DR

This paper applies a symmetry-based Power tensor technique to analyze PLANCK polarization maps, detecting statistically anisotropic multipoles and residual foreground effects across various angular scales, highlighting persistent anisotropies.

Contribution

The study introduces a novel symmetry-based Power tensor method to test statistical isotropy in CMB polarization maps, revealing anisotropies and residual foreground effects.

Findings

Detection of statistically anisotropic multipoles in PLANCK polarization maps.

Persistent anisotropic modes in NILC maps despite foreground cleaning.

Identification of potential residual foreground effects in galactic plane regions.

Abstract

We apply our symmetry based Power tensor technique to test conformity of PLANCK Polarization maps with statistical isotropy. On a wide range of angular scales (l=40-150), our preliminary analysis detects many statistically anisotropic multipoles in foreground cleaned full sky PLANCK polarization maps viz., COMMANDER and NILC. We also study the effect of residual foregrounds that may still be present in the galactic plane using both common UPB77 polarization mask, as well as the individual component separation method specific polarization masks. However some of the statistically anisotropic modes still persist, albeit significantly in NILC map. We further probed the data for any coherent alignments across multipoles in several bins from the chosen multipole range.