Paper: Systematic errors in cosmic microwave background polarization measurements

Systematic errors in cosmic microwave background polarization measurements
Daniel O'Dea, Anthony Challinor and Bradley R. Johnson

Abstract:
We investigate the impact of instrumental systematic errors on the potential
of cosmic microwave background polarization experiments targeting primordial
B-modes. To do so, we introduce spin-weighted Müller matrix-valued fields
describing the linear response of the imperfect optical system and receiver,
and give a careful discussion of the behaviour of the induced systematic
effects under rotation of the instrument. We give the correspondence between
the matrix components and known optical and receiver imperfections, and
compare the likely performance of pseudo-correlation receivers and those
that modulate the polarization with a half-wave plate. The latter is shown
to have the significant advantage of not coupling the total intensity into
polarization for perfect optics, but potential effects like optical
distortions that may be introduced by the quasi-optical wave plate warrant
further investigation. A fast method for tolerancing time-invariant
systematic effects is presented, which propagates errors through to power
spectra and cosmological parameters. The method extends previous studies to
an arbitrary scan strategy, and eliminates the need for time-consuming Monte
Carlo simulations in the early phases of instrument and survey design. We
illustrate the method with both simple parametrized forms for the
systematics and with beams based on physical-optics simulations. Example
results are given in the context of next-generation experiments targeting
tensor-to-scalar ratios r 0.01.

Source: Monthly Notices of the Royal Astronomical Society
http://www.blackwell-synergy.com/doi...6.2007.11558.x

Posted by
Robert Karl Stonjek