New Constraints on Anisotropic Rotation of CMB Polarization

TL;DR

This paper uses updated observational data to constrain the anisotropic rotation of CMB polarization caused by scalar fields, revealing tight limits on its variance and implications for scalar field physics.

Contribution

It provides the first model-independent constraints on the anisotropic rotation angle of CMB polarization using current data.

Findings

Anisotropic rotation variance is tightly constrained by observations.

The dominant effect of anisotropic rotation is its variance.

Current data limits the possible scalar field-induced polarization rotation.

Abstract

The coupling of a scalar field to electromagnetic field via the Chern-Simons term will rotate the polarization directions of the cosmic microwave background radiation. The rotation angle which relies on the distribution of the scalar field on the CMB sky is direction dependent. Such anisotropies will give rise to new distortions to the power spectra of CMB polarization and it can be used to probe the detailed physics of the scalar field. In this paper we use the updated observational data to constrain the anisotropic rotation angle in a model independent way. We find that the dominant effect of the anisotropic rotation on CMB comes from its variance and it is constrained tightly by the current data.