190 research outputs found
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.
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
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
Towards investigation of evolution of dynamical systems with independence of time accuracy: more classes of systems
The recently developed method (Paper 1) enabling one to investigate the
evolution of dynamical systems with an accuracy not dependent on time is
developed further. The classes of dynamical systems which can be studied by
that method are much extended, now including systems that are; (1)
non-Hamiltonian, conservative; (2) Hamiltonian with time-dependent
perturbation; (3) non-conservative (with dissipation). These systems cover
various types of N-body gravitating systems of astrophysical and cosmological
interest, such as the orbital evolution of planets, minor planets, artificial
satellites due to tidal, non-tidal perturbations and thermal thrust, evolving
close binary stellar systems, and the dynamics of accretion disks.Comment: Eur. Phys. Journ. C (in press), to match the published version, 4
page
The cosmological constant derived via galaxy groups and clusters
The common nature of dark matter and dark energy is argued in [1] based on
the approach that the cosmological constant \Lambda enters the weak-field
General Relativity following from Newton theorem on the "sphere-point mass"
equivalency [2]. Here we probe the \Lambda-gravity description of dark matter
in galaxy systems, from pairs up to galaxy clusters using the data of various
sources, i.e. of Local Supercluster galaxy surveys, gravity lensing and Planck
satellite. The prediction that the cosmological constant has to be the lower
limit for the weak-field \Lambda obtained from galaxy systems of various degree
of virialization is shown to be supported by those observations. The results
therefore support the \Lambda-gravity nature of dark matter in the studied
systems, implying that the positivity of the cosmological constant might be
deduced decades ago from the dynamics of galaxies and galaxy clusters far
before the cosmological SN surveys.Comment: To appear in Eur Phys J C, 7 page
On the Numerical Study of the Complexity and Fractal Dimension of CMB Anisotropies
We consider the problem of numerical computation of the Kolmogorov complexity
and the fractal dimension of the anisotropy spots of Cosmic Microwave
Background (CMB) radiation. Namely, we describe an algorithm of estimation of
the complexity of spots given by certain pixel configuration on a grid and
represent the results of computations for a series of structures of different
complexity. Thus, we demonstrate the calculability of such an abstract
descriptor as the Kolmogorov complexity for CMB digitized maps. The correlation
of complexity of the anisotropy spots with their fractal dimension is revealed
as well. This technique can be especially important while analyzing the data of
the forthcoming space experiments.Comment: LATEX, 3 figure
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