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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. 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{sup −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, potentiallymore » enabling its statistical subtraction from the measured 21 cm power spectrum.« less

Authors:
; ; ;  [1]; ; ;  [2];  [3];  [4];  [5]
  1. Department of Physics and Electronics, Rhodes University, P.O. Box 94, Grahamstown, 6140 (South Africa)
  2. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States)
  3. Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287 (United States)
  4. Berkeley Center for Cosmological Physics, Berkeley, CA 94720 (United States)
  5. Dept. of Astronomy, University of California, Berkeley, CA 94720 (United States)
Publication Date:
OSTI Identifier:
22679766
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 848; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; AVOIDANCE; COSMOLOGY; FARADAY EFFECT; POLARIZATION; RED SHIFT; SIMULATION; SPECTRA; STARS; VISIBILITY

Citation Formats

Nunhokee, C. D., Bernardi, G., Foster, G., Grobler, T. L., Kohn, S. A., Aguirre, J. E., Martinot, J. Z. E., Thyagarajan, N., Dillon, J. S., and Parsons, A. R., E-mail: cnunhokee@gmail.com. Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8B73.
Nunhokee, C. D., Bernardi, G., Foster, G., Grobler, T. L., Kohn, S. A., Aguirre, J. E., Martinot, J. Z. E., Thyagarajan, N., Dillon, J. S., & Parsons, A. R., E-mail: cnunhokee@gmail.com. Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme. United States. doi:10.3847/1538-4357/AA8B73.
Nunhokee, C. D., Bernardi, G., Foster, G., Grobler, T. L., Kohn, S. A., Aguirre, J. E., Martinot, J. Z. E., Thyagarajan, N., Dillon, J. S., and Parsons, A. R., E-mail: cnunhokee@gmail.com. Tue . "Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme". United States. doi:10.3847/1538-4357/AA8B73.
@article{osti_22679766,
title = {Constraining Polarized Foregrounds for EoR Experiments. II. Polarization Leakage Simulations in the Avoidance Scheme},
author = {Nunhokee, C. D. and Bernardi, G. and Foster, G. and Grobler, T. L. and Kohn, S. A. and Aguirre, J. E. and Martinot, J. Z. E. and Thyagarajan, N. and Dillon, J. S. and Parsons, A. R., E-mail: cnunhokee@gmail.com},
abstractNote = {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. 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{sup −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.},
doi = {10.3847/1538-4357/AA8B73},
journal = {Astrophysical Journal},
number = 1,
volume = 848,
place = {United States},
year = {Tue Oct 10 00:00:00 EDT 2017},
month = {Tue Oct 10 00:00:00 EDT 2017}
}