scholarly journals DARK ENERGY AND KEY PHYSICAL PARAMETERS OF CLUSTERS OF GALAXIES

2013 ◽  
Vol 53 (A) ◽  
pp. 550-554
Author(s):  
Gennady S. Bisnovatyi-Kogan ◽  
Artur Chernin ◽  
Marco Merafina
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Local Density ◽  
Critical Value ◽  
Virgo Cluster ◽  
Physical Parameters ◽  
Zero Gravity ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Static Solutions

We study physics of clusters of galaxies embedded in the cosmic dark energy background. The equilibrium and stability of polytropic spheres with equation of state of the matter             <em>P = Kp<sup>γ</sup></em>, <em>γ</em> = 1 + 1/n, in presence of a non-zero cosmological constant is investigated. The equilibrium state exists only for central densities <em>p</em><sub>0</sub> larger than the critical value <em>p</em><sub>c</sub> and there are no static solutions at <em>p</em><sub>0</sub>&lt;<em>p</em><sub>c</sub>. At this density the radius of the configuration is equal to the zero-gravity radius, at which the dark matter gravity is balanced by the dark energy antigravity. It is shown, that dark energy reduces the dynamic stability of the configuration. We show that the dynamical effects of dark energy are strong in clusters like the Virgo cluster, which halo radius is close to the zero-gravity radius. It is shown, that the empirical data on clusters like the Virgo cluster or the Coma cluster, are consistent with the assumption that the local density of dark energy on the scale of clusters of galaxies is the same as on the global cosmological scales.

80 MHz Survey of Extra-Galactic X-ray Sources

1979 ◽  
Vol 3 (5) ◽  
pp. 332-341 ◽  
Author(s):  
O. B. Slee ◽  
P. J. Quinn
Keyword(s):  
Angular Size ◽  
Virgo Cluster ◽  
Relativistic Electrons ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Microwave Background ◽  
Significant Information ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Bremsstrahlung Emission

The completion of the Uhuru (Forman et al. 1978) and Ariel V (Cooke et al. 1978) surveys of the sky for X-ray emission has resulted in many proposed identifications with individual galaxies and clusters of galaxies. The X-ray positions are not usually accurate enough to enable a positive identification to be made of the X-ray sources with optical or radio objects, and hence the identification is often based on statistical arguments — viz., the unexpected occurrence of unusual galaxies, radio sources or clusters of galaxies within or near the X-ray error boxes. There is usually no significant information available on the angular size of the X-ray emitter but in two or three cases (e.g. Perseus cluster, Coma cluster and Virgo cluster) the angular resolution is good enough to identify a broad component with dimensions approaching those of the whole cluster. This extended X-ray emission has been ascribed to either inverse Compton scattering of the 3° microwave background by relativistic electrons in the intra-cluster medium or to thermal-bremsstrahlung emission by an optically thin plasma at - 10s K.

scholarly journals Dark Matter in Groups and Clusters of Galaxies

2000 ◽  
Vol 174 ◽  
pp. 360-372 ◽  
Author(s):  
Jaan Einasto ◽  
Maret Einasto
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Dynamical Evolution ◽  
Constant Term ◽  
Stellar Populations ◽  
Clusters Of Galaxies ◽  
Baryonic Matter ◽  
Dark Matter Halos ◽  
Hot Gas ◽  
The Universe

AbstractWe compare the characteristics of stellar populations with those of dark halos. Dark matter around galaxies, and in groups, clusters and voids is discussed. Modern data suggest that the overall density of matter in the Universe is ΩM = 0.3 ± 0.1, about 80 % of this matter is nonbaryonic dark matter, and about 20 % is baryonic, mostly in the form of hot intra-cluster and intragroup gas, the rest in stellar populations of galaxies. All bright galaxies are surrounded by dark matter halos of external radii 200 − 300 kpc; halos consist mostly of non-baryonic matter with some mixture of hot gas. The Universe is dominated by dark energy (cosmological constant) term. Dark matter dominates in the dynamical evolution of galaxies in groups and clusters.

Overview of astroparticle physics and dark matter searches

2007 ◽  
Vol 22 (31) ◽  
pp. 5735-5746
Author(s):  
Nathalie Palanque-Delabrouille
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Acoustic Oscillation ◽  
Type Ia Supernovae ◽  
Clusters Of Galaxies ◽  
Astroparticle Physics ◽  
The Status ◽  
Type Ia ◽  
Ia Supernovae ◽  
The Impact

We present a general overview of recent results in the searches for dark matter and dark energy. We discuss the observation of the collision between two clusters of galaxies, and the impact this has on the relevance of dark matter. We then present the final results from microlensing experiments, which aimed at detecting dark baryonic objects in the halo of our galaxy, and the status of direct searches for WIMPs. We present the evidence for dark energy which initially comes from experiments dedicated to the study of distant type Ia supernovae. The measure of the baryon acoustic oscillation, an independent probe of the evolution of our universe that has recently brought interesting constraints, is finally described.

Super Plastic Flow and Cosmic Micromechanics

2007 ◽  
Vol 345-346 ◽  
pp. 577-580 ◽  
Author(s):  
Juan Daniel Muñoz-Andrade
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Plastic Flow ◽  
Volume Fraction ◽  
Relativistic Cosmology ◽  
Clusters Of Galaxies ◽  
Spatially Extended ◽  
Super Plastic ◽  
New Interpretation ◽  
The Universe

A unified interpretation of super plastic flow (SPF) and cosmic micromechanics in spatially extended single and polycrystalline systems (SESPS) allows determined that the nature of the hyperbolic granular flow in SESPS is assisted by the movement of dislocations as the pattern of the inner dimension flow. Consequently in this work a mathematical model related with relativistic cosmology and quantum mechanics is used in order to obtain the activation energy for super plastic flow in SESPS. This correspondence law between SPF and cosmic micromechanics is important in the light of recent cosmological theories of the existence of dark matter and dark energy in the cosmic structure, because in this new interpretation of the universe the planets, stars, galaxies, clusters of galaxies, etc., are considered as precipitates on dislocations in the cosmic structure, which is formed in a nature way by the dark matter and dark energy, in a similar form of precipitates on dislocations in a SESPS of metals. Physically in this context the expansion process of the universe is highly dependent upon the volume fraction, size and distribution of precipitates on dislocations in the cosmic structure. Therefore, in this work the main results obtained in cosmic micromechanics and cosmic macromechanics are related with the Max Planck’s scale (MPE) and Edwin Hubble’s scale (EHS) respectively.

scholarly journals Large Scale Gradient in the Velocity Field of the Coma Cluster and a Study of the Spin Orientation of Galaxies in the Virgo Cluster

1999 ◽  
Vol 186 ◽  
pp. 413-413
Author(s):  
M. Iye ◽  
T. Ozawa
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Virgo Cluster ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Spin Orientation ◽  
Angular Momenta ◽  
Physical Clusters

This paper reports two studies on the distribution of the spin angular momenta of galaxies in physical clusters of galaxies.

scholarly journals Dark energy and key physical parameters of clusters of galaxies

2011 ◽  
Vol 338 (2) ◽  
pp. 337-343 ◽  
Author(s):  
G. S. Bisnovatyi-Kogan ◽  
A. D. Chernin
Keyword(s):  
Dark Energy ◽  
Physical Parameters ◽  
Clusters Of Galaxies

Effective masses in a dense fermion background — Applied to neutrinos, dark matter and dark energy

2014 ◽  
Vol 29 (21) ◽  
pp. 1444010
Author(s):  
Bruce H. J. McKellar ◽  
T. J. Goldman ◽  
G. J. Stephenson
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Effective Mass ◽  
Negative Pressure ◽  
Expectation Value ◽  
Effective Masses ◽  
Neutrino Astrophysics

If fermions interact with a scalar field, and there are many fermions present the scalar field may develop an expectation value and generate an effective mass for the fermions. This can lead to the formation of fermion clusters, which could be relevant for neutrino astrophysics and for dark matter astrophysics. Because this system may exhibit negative pressure, it also leads to a model of dark energy.

Dark Matter and Dark Energy from the solution of the strong CP problem

2006 ◽  
Author(s):  
Roberto Mainini ◽  
Loris Colombo ◽  
Silvio Bonometto
Keyword(s):  
Dark Matter ◽  
Dark Energy

scholarly journals Neutrino dark matter in clusters of galaxies

2000 ◽  
Vol 2 ◽  
pp. 11-11 ◽  
Author(s):  
R A Treumann ◽  
A Kull ◽  
H Böhringer
Keyword(s):  
Dark Matter ◽  
Clusters Of Galaxies
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