2 research outputs found
Bianchi Type III String Cosmological Models with Time Dependent Bulk Viscosity
Bianchi type III string cosmological models with bulk viscous fluid for
massive string are investigated. To get the determinate model of the universe,
we have assumed that the coefficient of bulk viscosity () is inversely
proportional to the expansion () in the model and expansion ()
in the model is proportional to the shear (). This leads to , and are constants. The behaviour of the model in presence
and absence of bulk viscosity, is discussed. The physical implications of the
models are also discussed in detail.Comment: 11 pages, no figur
Cosmic Microwave Background Anisotropy Window Functions Revisited
The primary results of most observations of cosmic microwave background (CMB)
anisotropy are estimates of the angular power spectrum averaged through some
broad band, called band-powers. These estimates are in turn what are used to
produce constraints on cosmological parameters due to all CMB observations.
Essential to this estimation of cosmological parameters is the calculation of
the expected band-power for a given experiment, given a theoretical power
spectrum. Here we derive the "band power" window function which should be used
for this calculation, and point out that it is not equivalent to the window
function used to calculate the variance. This important distinction has been
absent from much of the literature: the variance window function is often used
as the band-power window function. We discuss the validity of this assumed
equivalence, the role of window functions for experiments that constrain the
power in {\it multiple} bands, and summarize a prescription for reporting
experimental results. The analysis methods detailed here are applied in a
companion paper to three years of data from the Medium Scale Anisotropy
Measurement.Comment: 5 pages, 1 included .eps figure, PRD in press---final published
versio