Search for Gravitational Waves in the CMB After WMAP3: Foreground Confusion and The Optimal Frequency Coverage for Foreground Minimization

Abstract

B-modes of Cosmic Microwave Background (CMB) polarization can be created by a primordial gravitational wave background. If this background was created by Inflation, then the amplitude of the polarization signal is proportional the energy density of the universe during inflation. The primordial signal will be contaminated by polarized foregrounds including dust and synchrotron emission within the galaxy. In light of the WMAP polarization maps, we consider the ability of several hypothetical CMB polarization experiments to separate primordial CMB B-mode signal from galactic foregrounds. We also study the optimization of a CMB experiment with a fixed number of detectors in the focal plane to determine how the detectors should be distributed in different frequency bands to minimize foreground confusion. We show that the optimal configuration requires observations in at least 5 channels spread over the frequency range between 30 GHz and 500 GHz with substantial coverage around 150 GHz. If a low-resolution space experiment using 1000 detectors to reach a noise level of about 1000 nK${}^2$ concentrates on roughly 66% of the sky with the least foreground contamination the minimum detectable level of the tensor-to-scalar ratio would be about 0.002 at the 99% confidence level for an optical depth of 0.1.

13 pages, 8 figures, replaced to match the accepted version in PRD

References in corpus (1)

• Cosmological Information from Lensed CMB Power Spectra

Cited by in corpus (16)

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• Inflationary Cosmology Connecting Dark Energy and Dark Matter
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• Impact of reionization on CMB polarization tests of slow-roll inflation
• Detecting relic gravitational waves in the CMB: Comparison of different methods
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• Stable indications of relic gravitational waves in Wilkinson Microwave Anisotropy Probe data and forecasts for the Planck mission
• Effects of Destriping Errors on CMB Polarisation Power Spectra and and Pixel Noise Covariances
• Subdegree Sunyaev-Zel'dovich Signal from Multifrequency BOOMERanG observations
• Chiral primordial gravitational waves in extended theories of Scalar-Tensor gravity
• Constraints on the SZ Power Spectrum on Degree Angular Scales in WMAP Data