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Full-Text Articles in Physical Sciences and Mathematics
Constraining F(R) Gravity As A Scalar-Tensor Theory, Thomas Faulkner, Max Tegmark, Emory F. Bunn, Yi Mao
Constraining F(R) Gravity As A Scalar-Tensor Theory, Thomas Faulkner, Max Tegmark, Emory F. Bunn, Yi Mao
Physics Faculty Publications
We search for viable f(R) theories of gravity, making use of the equivalence between such theories and scalar-tensor gravity. We find that models can be made consistent with solar system constraints either by giving the scalar a high mass or by exploiting the so-called chameleon effect. However, in both cases, it appears likely that any late-time cosmic acceleration will be observationally indistinguishable from acceleration caused by a cosmological constant. We also explore further observational constraints from, e.g., big bang nucleosynthesis and inflation.
Directionality In The Wilkinson Microwave Anisotropy Probe Polarization Data, D. Hanson, Douglas Scott, Emory F. Bunn
Directionality In The Wilkinson Microwave Anisotropy Probe Polarization Data, D. Hanson, Douglas Scott, Emory F. Bunn
Physics Faculty Publications
Polarization is the next frontier of cosmic microwave background analysis, but its signal is dominated over much of the sky by foregrounds which must be carefully removed. To determine the efficacy of this cleaning, it is necessary to have sensitive tests for residual foreground contamination in polarization sky maps. The dominant Galactic foregrounds introduce a large-scale anisotropy on to the sky, so it makes sense to use a statistic sensitive to overall directionality for this purpose. Here, we adapt the rapidly computable D statistic of Bunn and Scott to polarization data, and demonstrate its utility as a foreground monitor by …
Systematic Errors In Cosmic Microwave Background Interferometry, Emory F. Bunn
Systematic Errors In Cosmic Microwave Background Interferometry, Emory F. Bunn
Physics Faculty Publications
Cosmic microwave background (CMB) polarization observations will require superb control of systematic errors in order to achieve their full scientific potential, particularly in the case of attempts to detect the B modes that may provide a window on inflation. Interferometry may be a promising way to achieve these goals. This paper presents a formalism for characterizing the effects of a variety of systematic errors on interferometric CMB polarization observations, with particular emphasis on estimates of the B-mode power spectrum. The most severe errors are those that couple the temperature anisotropy signal to polarization; such errors include cross talk within …
Mosaicking With Cosmic Microwave Background Interferometers, Emory F. Bunn, Martin White
Mosaicking With Cosmic Microwave Background Interferometers, Emory F. Bunn, Martin White
Physics Faculty Publications
Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, which is valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for CMB interferometry, including both temperature and polarization, to mosaics of observations covering arbitrarily large areas of the sky, with each individual pointing lying within the flat-sky approximation. We present a method for computing the correlation between visibilities with arbitrary pointing …