Constraining Polarized Foregrounds for EoR Experiments I: 2D Power
  Spectra from the PAPER-32 Imaging Array
  Current-generation low frequency interferometers constructed with the
objective of detecting the high-redshift 21 cm background, aim to generate
power spectra of the brightness-temperature contrast of neutral hydrogen in
primordial intergalactic medium. Two-dimensional power spectra (power in
Fourier modes parallel and perpendicular to the line of sight) formed from
interferometric visibilities have been shown to delineate a boundary between
spectrally-smooth foregrounds (known as the wedge) and spectrally-structured 21
cm background emission (the EoR-window). However, polarized foregrounds are
known to possess spectral structure due to Faraday rotation, which can leak
into the EoR window. In this work, we create and analyze 2D power spectra from
the PAPER-32 imaging array in Stokes I, Q, U and V. These allow us to observe
and diagnose systematic effects in our calibration at high signal-to-noise
within the Fourier space most relevant to EoR experiments. We observe
well-defined windows in the Stokes visibilities, with Stokes Q, U and V power
spectra sharing a similar wedge shape to that seen in Stokes I. With modest
polarization calibration, we see no evidence that polarization calibration
errors move power outside the wedge in any Stokes visibility, to the noise
levels attained. Deeper integrations will be required to confirm that this
behavior persists to the depth required for EoR detection.
