20,437 research outputs found
Maximum likelihood analysis of systematic errors in interferometric observations of the cosmic microwave background
We investigate the impact of instrumental systematic errors in
interferometric measurements of the cosmic microwave background (CMB)
temperature and polarization power spectra. We simulate interferometric CMB
observations to generate mock visibilities and estimate power spectra using the
statistically optimal maximum likelihood technique. We define a quadratic error
measure to determine allowable levels of systematic error that do not induce
power spectrum errors beyond a given tolerance. As an example, in this study we
focus on differential pointing errors. The effects of other systematics can be
simulated by this pipeline in a straightforward manner. We find that, in order
to accurately recover the underlying B-modes for r=0.01 at 28<l<384,
Gaussian-distributed pointing errors must be controlled to 0.7^\circ rms for an
interferometer with an antenna configuration similar to QUBIC, in agreement
with analytical estimates. Only the statistical uncertainty for 28<l<88 would
be changed at ~10% level. With the same instrumental configuration, we find the
pointing errors would slightly bias the 2-\sigma upper limit of the
tensor-to-scalar ratio r by ~10%. We also show that the impact of pointing
errors on the TB and EB measurements is negligibly small.Comment: 10 pages, 4 figures, accepted for publication in ApJS. Includes
improvements in clarity of presentation and Fig.4 added, in response to
refere
A First Map of the CMB at 0.5Deg Resolution
We use a Maximum Entropy technique to reconstruct a map of the microwave sky
near the star Gamma Ursae Minoris, based on data from flights 2, 3 and 4 of the
Millimeter-wave Anisotropy eXperiment (MAX).Comment: 5 pages plus 3 postscript figures, uuencoded compressed postscript,
CfPA-94-TH-5
Effectiveness of external factors to reduce the risk of dehydration in older people living in residential care: a systematic review
GOVERNMENT POLICY, WIND EROSION, AND ECONOMIC VIABILITY IN SEMI-ARID AGRICULTURE: THE CASE OF THE SOUTHERN TEXAS HIGH PLAINS
The 1996 farm bill challenges agricultural producers to pursue conservation objectives while allowing flexibility and reducing subsidies. The nature of this challenge for semi-arid rainfed, wind-erosion-prone agriculture is explored via a behavioral model. Simulations of farm-firm decision making under scenarios in the southern Texas High Plains are evaluated. Results indicate that the removal of subsidies, while lowering farm incomes, does not, under most assumptions, alter cropping system choice. Alternatively, under a variety of assumptions, the imposition of an erosion tax shuts down cropping.Conservation practices, Cropping system choice, Economic dynamics, FAIR Act of 1996, Agricultural and Food Policy,
Fisher Matrix Optimization of Cosmic Microwave Background Interferometers
We describe a method for forecasting errors in interferometric measurements
of polarization of the cosmic microwave background (CMB) radiation, based on
the use of the Fisher matrix calculated from the visibility covariance and
relation matrices. In addition to noise and sample variance, the method can
account for many kinds of systematic error by calculating an augmented Fisher
matrix, including parameters that characterize the instrument along with the
cosmological parameters to be estimated. The method is illustrated with
examples of gain errors and errors in polarizer orientation. The augmented
Fisher matrix approach is applicable to a much wider range of problems beyond
CMB interferometry.Comment: Phys. Rev. D 93, 023512 (2016), v4 has no further change
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