Simulations of Galactic polarized synchrotron emission for Epoch of Reionization observations

TL;DR

This paper presents new full-sky simulations of polarized Galactic synchrotron emission at low frequencies to improve modeling of foreground contamination in Epoch of Reionization 21cm observations.

Contribution

The work provides the first detailed, publicly available simulations of polarized synchrotron emission in the 50-200 MHz range for EoR studies, accounting for Faraday rotation effects.

Findings

Simulated polarized maps match observed properties of diffuse emission.

These maps help evaluate foreground removal techniques.

They enable testing of instrumental leakage effects.

Abstract

The detection of the redshifted cosmological $21$~cm line signal requires the removal of the Galactic and extragalactic foreground emission, which is orders of magnitude brighter anywhere in the sky. Foreground cleaning methods currently used are efficient in removing spectrally smooth components. However, they struggle in the presence of not spectrally smooth contamination that is, therefore, potentially the most dangerous one. An example of this is the polarized synchrotron emission, which is Faraday rotated by the interstellar medium and leaks into total intensity due to instrumental imperfections. In this work we present new full-sky simulations of this polarized synchrotron emission in the $50-200$~MHz range, obtained from the observed properties of diffuse polarized emission at low frequencies. The simulated polarized maps are made publicly available, aiming to provide more realistic templates to simulate the effect of instrumental leakage and the effectiveness of foreground separation techniques.