E and B polarizations from inhomogeneous and solar surface turbulence

TL;DR

This paper investigates how inhomogeneous and solar surface turbulence influence E- and B-mode polarization signals, revealing that only inhomogeneous helical turbulence can produce parity-odd polarization, and explaining observed EE/BB ratios.

Contribution

It demonstrates that inhomogeneous helical turbulence uniquely generates parity-odd polarization signals and links nonhelical turbulence skewness to EE/BB ratio enhancements, with applications to solar polarization analysis.

Findings

Only inhomogeneous helical turbulence produces parity-odd polarization signals.

Nonvanishing skewness of E polarization enhances EE/BB ratio.

Solar polarization can help characterize helical turbulence without magnetic inversion.

Abstract

Gradient- and curl-type or E- and B-type polarizations have been routinely analyzed to study the physics contributing to the cosmic microwave background polarization and galactic foregrounds. They characterize the parity-even and parity-odd properties of the underlying physical mechanisms, for example hydromagnetic turbulence in the case of dust polarization. Here we study spectral correlation functions characterizing the parity-even and parity-odd parts of linear polarization for homogeneous and inhomogeneous turbulence to show that only the inhomogeneous helical case can give rise to a parity-odd polarization signal. We also study nonhelical turbulence and suggest that a strong nonvanishing (here negative) skewness of the E polarization is responsible for an enhanced ratio of the EE to the BB (quadratic) correlation in both helical and nonhelical cases. This could explain the enhanced EE/BB ratio observed recently for dust polarization. We close with a preliminary assessment of using linear polarization of the Sun to characterize its helical turbulence without being subjected to the pi ambiguity that magnetic inversion techniques have to address.