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Бисноватый-Коган Геннадий
Семенович, гнс, отдел 64
Цикл из
2-х работ: Космологические объекты при наличии темной энергии
1)
Galaxy clusters in
presence of dark energy: a kinetic approach
M. Merafina, G. S. Bisnovatyi-Kogan, and M. Donnari,
Astronomy & Astrophysics 568, A93 (2014)
ABSTRACT
Context. The external regions of
galaxy clusters may be under strong influence of the dark energy, which was
discovered by observations of supernovae Ia
at redshift z
< 1. The presence of the dark
energy in the gravitational equilibrium equation, with the Einstein Λ term, balances the gravity, and extends the
equilibrium configuration more in radius.
Aims. We investigate the features
of the equilibrium configurations to analyse how the
presence of the dark energy affects the density profiles and radial extension by specifying the conditions
for which the gravitational equilibrium begins.
Methods. We derived the kinetic
equation for an equilibrium configuration in presence of dark energy and solved
the gravitational equilibrium equation by considering a Maxwell-Boltzmann
distribution function with a cut-off in the framework of the Newtonian regime,
because the observed velocities of galaxies inside a cluster are much lower
than the velocity of light.
Results. The prevalence of dark energy
effects
on the gravity shows a wide region in the W0-ρΛ diagram where equilibrium solutions are not possible. In these particular
conditions, the galaxies located in the external regions of a cluster can flow
out, following the accelerating expansion of the Universe.
2)
Galactic Cluster in
the Presence of Dark Energy
G. S. Bisnovatyi-Kogan, Gravitation and Cosmology,
2014, Vol. 20, No. 3, pp. 157-164.
Abstract-A solution for cosmological
expansion in the presence of dark matter is presented, and observational
results from which a conclusion on the present value of the cosmological
constant is obtained, are discussed. A solution is obtained for hydrodynamic
outflow of polytropic
gas from a gravitating center, in the presence of uniform Dark Energy (DE). The
antigravity of DE is enlightening the outflow and makes the outflow possible at smaller initial
temperature at the same density. The main property of the wind in the presence
of DE is its unlimited acceleration after passing the critical point. Applying
this solution to winds from galaxy clusters, we suggest that a collision of a
strongly accelerated wind with another galaxy cluster, or with another galactic
cluster wind, could lead to the formation of highest energy cosmic rays.