535 research outputs found
Kolmogorov stochasticity parameter measuring the randomness in Cosmic Microwave Background
The Kolmogorov stochasticity parameter (KSP) is applied to quantify the
degree of randomness (stochasticity) in the temperature maps of the Cosmic
Microwave Background radiation maps. It is shown that, the KSP for the WMAP5
maps is about twice higher than that of the simulated maps for the concordance
\LambdaCDM cosmological model, implying the existence of a randomizing effect
not taken into account in the model. As was revealed recently, underdense
regions in the large scale matter distributions, i.e the voids, possess
hyperbolic and hence randomizing properties. The degree of randomness for the
Cold Spot appears to be about twice higher than the average over the mean
temperature level spots in the sky, which supports the void nature of the Cold
Spot. Kolmogorov's parameter then acts as a quantitative tracer of the voids
via CMB.Comment: A&A Lett (in press), 2 pages, 1 Tabl
Are There Echoes From The Pre-Big Bang Universe? A Search for Low Variance Circles in the CMB Sky
The existence of concentric low variance circles in the CMB sky, generated by
black-hole encounters in an aeon preceding our big bang, is a prediction of the
Conformal Cyclic Cosmology. Detection of three families of such circles in WMAP
data was recently reported by Gurzadyan & Penrose (2010). We reassess the
statistical significance of those circles by comparing with Monte Carlo
simulations of the CMB sky with realistic modeling of the anisotropic noise in
WMAP data. We find that the circles are not anomalous and that all three groups
are consistent at 3sigma level with a Gaussian CMB sky as predicted by
inflationary cosmology model
Recovering the Internal Dynamics and the Shapes of Galaxy Clusters: Virgo Cluster
We describe a method for recovering of the substructure, internal dynamics
and geometrical shapes of clusters of galaxies. Applying the method to the
Virgo cluster, we, first, reveal the substructure of the central 4 arc degree
field of the Virgo cluster by means of S-tree technique. The existence of three
main subgroups of galaxies is revealed and their dynamical characteristics are
estimated. Then, using the previously suggested technique (Gurzadyan and Rauzy
1997), the bulk flow velocities of the subgroups are evaluated based on the
distribution of the redshifts of the galaxies. The results enable us also to
obtain a secure indication of the elongation of the Virgo cluster and its
positional inclination.Comment: to appear in Int.Journ.Mod.Phys.
Ellipticity in Cosmic Microwave Background as a Tracer of Large-Scale Universe
Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data confirm the
ellipticity of anisotropies of Cosmic Microwave Background (CMB) maps, found
previously for Boomerang and WMAP 1-year high sensitivity maps. The low noise
level of the WMAP latter data enable also to show that, the ellipticity is a
property not described by the conventional cosmological model fitting the power
spectrum of CMB. As a large scale anomaly, the ellipticity characteristics are
consistent with the effect of geodesics mixing occurring in hyperbolic
Universe. Its relation to other large scale effects, i.e. to suppressed low
multipoles, as well as to dark energy if the latter is due to vacuum
fluctuations, is then an arising issue.Comment: to appear in Phys. Lett.
Collective relaxation of stellar systems revisited
The chaos in stellar systems is studied using the theory of dynamical systems
and the Van Kampen stochastic differential equation approach. The exponential
instability (chaos) of spherical N-body gravitating systems, already known
previously, is confirmed. The characteristic timescale of that instability is
estimated confirming the collective relaxation time obtained by means of the
Maupertuis principle.Comment: A & A (in press), 3 pages, to match the published versio
Kolmogorov cosmic microwave background sky
A new map of the sky representing the degree of randomness in the cosmic
microwave background (CMB) temperature has been obtained. The map based on
estimation of the Kolmogorov stochasticity parameter clearly distinguishes the
contribution of the Galactic disk from the CMB and reveals regions of various
degrees of randomness that can reflect the properties of inhomogeneities in the
Universe. For example, among the high randomness regions is the southern
non-Gaussian anomaly, the Cold Spot, with a stratification expected for the
voids. Existence of its counterpart, a Northern Cold Spot with almost identical
randomness properties among other low-temperature regions is revealed. By its
informative power, Kolmogorov's map can be complementary to the CMB temperature
and polarization sky maps.Comment: A & A (in press), to match the published version, 4 pages, 5 figs, 2
Table
Hidden invariance in Gurzadyan-Xue cosmological models
The dark energy formula derived by Gurzadyan and Xue which leads to a value
fitting the SN data, provides a scaling relation between the physical constants
and cosmological parameters and defines a set of cosmological models. In
previous works we have considered several of those models and derived the
cosmological equations for each case. In this letter, we present the phase
portrait analysis of those models. Surprisingly we found, first, that the
separatrix in the phase space which determines the character of solutions
depends solely on the value of the current matter density. Namely, at
the equations describe Friedmannian Universe with the classical
singularity at the beginning. While at all solutions for all
models start with zero density and non vanishing scale factor. Secondly, more
remarkable, the value defining the separatrix is the same
for all models, which reveales an underlying invariance hidden in the models,
possibly, due to the basic nature of the GX-scaling.Comment: to appear in Physics Letters
Chaotic Phenomena in Astrophysics and Cosmology
Chaos as typical property of non-linear systems has revealed its crucial role
in various problems of astrophysics and cosmology. The problems discussed at
these lectures include planetary dynamics, galactic dynamics, reconstruction of
the substructure of clusters of galaxies, instability in Wheeler-DeWitt
superspace. The choice of the problems aimed to show also the diversity of
approaches and mathematical tools, which include the geometric criterion
(Ricci) of relative instability in many dimensional systems, the estimation of
Kolmogorov-Sinai entropy, the hyperbolicity in pseudo-Riemannian spaces, etc.Comment: Lectures at the Xth Brazilian School of Cosmology and Gravitation,
July-August, Rio de Janeiro, 200
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