Realistic Simulations of the Galactic Polarized Foreground: Consequences for 21-cm Reionization Detection Experiments

TL;DR

This paper presents realistic simulations of Galactic polarized foregrounds, crucial for 21-cm EoR experiments, highlighting how polarized emission can mimic the EoR signal and affect detection.

Contribution

It introduces detailed simulations of Galactic synchrotron and free-free emission, including polarization and Faraday effects, for improved EoR foreground modeling.

Findings

Simulated polarized Galactic emission can mimic EoR signals.

Instrumental calibration errors can cause leakage of polarized into total intensity.

Realistic simulations are essential for accurate EoR detection strategies.

Abstract

Experiments designed to measure the redshifted 21~cm line from the Epoch of Reionization (EoR) are challenged by strong astrophysical foreground contamination, ionospheric distortions, complex instrumental response and other different types of noise (e.g. radio frequency interference). The astrophysical foregrounds are dominated by diffuse synchrotron emission from our Galaxy. Here we present a simulation of the Galactic emission used as a foreground module for the LOFAR- EoR key science project end-to-end simulations. The simulation produces total and polarized intensity over $10^\circ \times 10^\circ$ maps of the Galactic synchrotron and free-free emission, including all observed characteristics of the emission: spatial fluctuations of amplitude and spectral index of the synchrotron emission, together with Faraday rotation effects. The importance of these simulations arise from the fact that the Galactic polarized emission could behave in a manner similar to the EoR signal along the frequency direction. As a consequence, an improper instrumental calibration will give rise to leakages of the polarized to the total signal and mask the desired EoR signal. In this paper we address this for the first time through realistic simulations.