Title: Constraining Polarized Foregrounds for EOR Experiments II: Polarization Leakage Simulations in the Avoidance Scheme,
Abstract: A critical challenge in the observation of the redshifted 21-cm line is its
separation from bright Galactic and extragalactic foregrounds. In particular,
the instrumental leakage of polarized foregrounds, which undergo significant
Faraday rotation as they propagate through the interstellar medium, may
harmfully contaminate the 21-cm power spectrum. We develop a formalism to
describe the leakage due to instrumental widefield effects in visibility-based
power spectra measured with redundant arrays, extending the delay-spectrum
approach presented in Parsons et al. (2012). We construct polarized sky models
and propagate them through the instrument model to simulate realistic full-sky
observations with the Precision Array to Probe the Epoch of Reionization. We
find that the leakage due to a population of polarized point sources is
expected to be higher than diffuse Galactic polarization at any $k$ mode for a
30~m reference baseline. For the same reference baseline, a foreground-free
window at $k > 0.3 \, h$~Mpc$^{-1}$ can be defined in terms of leakage from
diffuse Galactic polarization even under the most pessimistic assumptions. If
measurements of polarized foreground power spectra or a model of polarized
foregrounds are given, our method is able to predict the polarization leakage
in actual 21-cm observations, potentially enabling its statistical subtraction
from the measured 21-cm power spectrum.