Characterization of the polarized synchrotron emission from Planck and WMAP data

TL;DR

This study characterizes the diffuse Galactic polarized synchrotron emission using Planck and WMAP data, revealing steep power spectra decay, low B/E ratio, and negligible EB correlation, crucial for understanding foregrounds in CMB polarization.

Contribution

It provides detailed measurements of polarized synchrotron power spectra and their spectral indices across multiple sky regions, improving foreground modeling for CMB studies.

Findings

EE and BB spectra decay steeply with multipole index

B/E ratio is approximately 0.22

EB correlation is consistent with zero

Abstract

The purpose of this work is to characterize the diffuse Galactic polarized synchrotron. We present EE, BB, and EB power spectra estimated cross-correlating Planck and WMAP polarization frequency maps at 23 and 30 GHz, for a set of six sky regions covering from 30% to 94% of the sky. The EE and BB angular power spectra show a steep decay of the spectral amplitude as a function of multipole, approximated by a power law with power indices around -2.9 for both components. The B/E ratio is about 0.22. The EB cross-component is compatible with zero at 1$\sigma$, with upper constraint on the EB/EE ratio of 1.2% at the 2$\sigma$ level. The recovered SED, in the frequency range 23-30 GHz, shows E and B power-law spectral indices compatible between themselves with a value of about -3.