Testing Isotropy of Cosmic Microwave Background Radiation

TL;DR

This paper introduces novel symmetry-based, rotationally invariant methods to test the isotropy of cosmic microwave background radiation, revealing significant anisotropy and alignments inconsistent with isotropic models.

Contribution

It presents new entropy-based measures and angular multipole analysis techniques that detect anisotropy and alignments in CMB data, surpassing traditional power spectrum methods.

Findings

Detection of 7 axes aligned with Virgo in CMB data.

Identification of 12 cases of significant anisotropy with low probability under isotropy.

Rejection of isotropy in ILC maps at confidence levels better than 99.9%.

Abstract

We introduce new symmetry-based methods to test for isotropy in cosmic microwave background radiation. Each angular multipole is factored into unique products of power eigenvectors, related multipoles and singular values that provide 2 new rotationally invariant measures mode by mode. The power entropy and directional entropy are new tests of randomness that are independent of the usual CMB power. Simulated galactic plane contamination is readily identified, and the new procedures mesh perfectly with linear transformations employed for windowed-sky analysis. The ILC -WMAP data maps show 7 axes well aligned with one another and the direction Virgo. Parameter free statistics find 12 independent cases of extraordinary axial alignment, low power entropy, or both having 5% probability or lower in an isotropic distribution. Isotropy of the ILC maps is ruled out to confidence levels of better than 99.9%, whether or not coincidences with other puzzles coming from the Virgo axis are included. Our work shows that anisotropy is not confined to the low l region, but extends over a much larger l range.