507 research outputs found
CMBFAST for spatially closed universes
We extend the cosmological linear perturbation theory code CMBFAST to closed
geometries. This completes the implementation of CMBFAST to all types of
geometries and allows the user to perform an unlimited search in the parameter
space of models. This will be specially useful for placing confidence limits on
cosmological parameters from existing and future data. We discuss some of the
technical issues regarding the implementation.Comment: 6 pages, 2 figures, new version of CMBFAST can be found
http://www.sns.ias.edu/~matiasz/CMBFAST/cmbfast.htm
Extended self-similarity of the small-scale cosmic microwave background anisotropy
The Extended Self-Similarity (ESS) of cosmic microwave background (CMB)
radiation has been studied using recent data obtained by the space-craft based
Wilkinson Microwave Anisotropy Probe. Using the ESS and the high angular scale
resolution (arcminutes) of the data it is shown that the CMB temperature space
{\it increments} exhibit considerable and systematic declination from
Gaussianity for high order moments at the small angular scales. Moreover, the
CMB space increment ESS exponents have remarkably close values to the ESS
exponents observed in turbulence (in magnetohydrodynamic turbulence)
Gravitational Lensing of the Microwave Background by Galaxy Clusters
Galaxy clusters will distort the pattern of temperature anisotropies in the
microwave background via gravitational lensing. We create lensed microwave
background maps using clusters drawn from numerical cosmological simulations. A
distinctive dipole-like temperature fluctuation pattern is formed aligned with
the underlying microwave temperature gradient. For a massive cluster, the
characteristic angular size of the temperature distortion is a few arcminutes
and the characteristic amplitude a few micro-Kelvin. We demonstrate a simple
technique for estimating the lensing deflection induced by the cluster;
microwave background lensing measurements have the potential to determine the
mass distribution for some clusters with good accuracy on angular scales up to
a few arcminutes. Future high-resolution and high-sensitivity microwave
background maps will have the capability to detect lensing by clusters; we
discuss various systematic limitations on probing cluster masses using this
technique.Comment: 8 pages, 8 figures. Expanded discussion of systematic errors and kSZ
effect, including new figure; version accepted by Ap
- …