Joint 3D modelling of the polarized Galactic synchrotron and thermal dust foreground diffuse emission

TL;DR

This paper develops a comprehensive 3D model of polarized Galactic synchrotron and thermal dust emissions, integrating magnetic fields and matter distribution, to better understand and mitigate foreground contamination in CMB polarization measurements.

Contribution

It introduces the first coherent 3D model of both synchrotron and dust polarized emissions, combining magnetic field and matter distribution models to improve foreground predictions for CMB studies.

Findings

Model reproduces large-scale structures observed in data.

Best-fit parameters align with previous estimates from synchrotron and pulsar data.

Foreground contamination can dominate CMB B-mode signals at certain frequencies and scales.

Abstract

We present for the first time a coherent model of the polarized Galactic synchrotron and thermal dust emissions which are the main diffuse foreground for the measurement of the polarized power spectra of the CMB fluctuations with the Planck satellite mission. We produce 3D models of the Galactic magnetic field including regular and turbulent components, and of the distribution of matter in the Galaxy, relativistic electrons and dust grains. By integrating along the line of sight we construct maps of the polarized Galactic synchrotron and thermal dust emission for each of these models and compare them to currently available data. We consider the 408 MHz all-sky continuum survey, the 23 GHz band of the Wilkinson Microwave Anisotropy Probe and the 353 GHz Archeops data.}{The best-fit parameters obtained are consistent with previous estimates in the literature based only on synchrotron emission and pulsar rotation measurements. They allows us to reproduce the large scale structures observed on the data. Poorly understood local Galactic structures and turbulence make difficult an accurate reconstruction of the observations in the Galactic plane. Finally, using the best-fit model we are able to estimate the expected polarized foreground contamination at the Planck frequency bands. For the CMB bands, 70, 100, 143 and 217 GHz, at high Galactic latitudes although the CMB signal dominates in general, a significant foreground contribution is expected at large angular scales. In particular, this contribution will dominate the CMB signal for the B modes expected from realistic models of a background of primordial gravitational waves.