[en] Modern state of observation cosmology is briefly discussed. Among other things, a problem, related to Hibble constant and slowdown constant determining is considered. Within ''pancake'' theory hot (neutrino) cosmological model explains well the large-scale structure of the Universe, but does not explain the galaxy formation. A cold cosmological model explains well light object formation, but contradicts data on large-scale structure

[en] It is shown that the motion of the solar system relative to the relic background radioemission alows to predict for the future observation the magnitude of regular proper motion of all extragalactic objects. The numerous mass measurement of that effect with the aid of cosmic radio interferometers will probably allow to determine the basic parameters of the cosmological model

[en] This paper discusses a model of physical processes that occur in the center of the Galaxy and cause the emission of the 511 keV annihilation γ - line and of a continuous γ - spectrum. The hypothesis of the paper is that electron positron pairs whose annihilation produces the observed γ - line are formed when a gas-cloud target is irradiated by a directed beam of hard (approx. 100 MeV) γ-quanta. A model is developed that shows how a γ - beam (γ-gun) forms near a supermassive rotating black-hole surrounded by a gaseous accretion disk with a magnetic field. The results of numerical simulations are compared with observational data. 40 references, 4 figures, 1 table

[en] It is shown that the solution of the Friedmann equation with negative vacuum density and with an account for the density of strings going beyond the horizon (infinite strings) is the same for spaces of negative, zero and positive curvature. This is connected with the fact that in the equation the term, accounting for the space curvature, and the term describing the strings have the same structure. The model presented satisfies the value of the deceleration parameter q₀0.5, of the expansion parameter H₀=50 km/s x Mpc, and yields the age of the Universe from the beginning of the expansion of 16 billion years. The model also predicts a stop in the expansion and the subsequent contraction of the Universe. For a flat space and for the present density of the nonrelativistic matter 5x10^-31 g/cm³, the model yields the vacuum density - 2x10^-30 g/cm³, the string density 6x10^-30 g/cm³; the stop will occur 43 billion years after the beginning of the expansion. Other features of the model as well as possible observational tests are discussed

[en] The observational data seem to indicate that the visible matter in our universe is concentrated inside a sphere with radius corresponding to red shift z∼5. A model which explains this phenomenon is presented. The cosmological evolution of the baryon island and the observational consequences of this hypothesis are discussed

[en] It is demonstrated that, for a certain type of hidden mass (negative vacuum density and system of infinite domain walls), a positive curvature cosmological model can realize a regime of periodic oscillations of the Universe without approaching singularity or even a steady-state regime. The possibility of evolution from the inflation and phase-transition stage to periodic oscillation and steady-state is considered. An opportunity for observational testing and some unresolved problems for the model are also considered. (author)

[en] The dependence of the force of radiative slowing-down of relativistic electrons and positrons on their energy is studied for different elementary processes of interaction: Thomson, lompton, cyclotron scattering and e^+- pair production. It is shown that these processes may exert significant influence on the acceleration of electrons and positrons by the electric field in magnetospheres of active neutron stars. The possibility of generation of hard gamma-ray radiation as a result of the processes considered as discussed and some astrophysical implications are presented

[en] The observational data seem to indicate that the visible matter in the Universe is concentrated in a sphere with the radius which corresponds to a redshift z ∼ 5. A model is presented which explains this phenomenon. The cosmological evolution of the baryon island is discussed and the observational consequences of the hypothesis are considered

[en] Paper discusses a model of physical processes that occur in the center of the Galaxy and cause the emission of the 511 keV annihilation γ-ray line and of the continuous γ-ray spectrum. According to the hypothesis suggested in the paper, electron-positron pairs, whose annihilation produces the γ-ray line and the continuum, are formed when a gas-cloud target is irradiated by a directed beam of hard (approximately 100 MeV) gamma-ray quanta. A model is developed of how a γ-ray beam (gamma-ray gun) is formed near a supermassive rotating black hole surrounded by an accretion gaseous disk with a magnetic field. The results of numerical simulations are compared with the observational data. The model of γ-ray gun permits in the framework of reasonable suppositions to obtain both high enough efficiency of line formation (10^-4-10^-3) and the required ratio between the intensity of γ-lines and continuous γ-spectrum in its vicinity. The observed sharp break (or even the maximum) near 2 MeV is explained in the framework of the model. γ-line and continuous spectrum variation can be explained by the changes both in the target and in the source

[en] Propagation of an electromagnetic wave in the field of gravitational waves is considered. Attention is given to the principal difference between the electromagnetic wave propagation in the field of random gravitational waves and the electromagnetic wave propagation in a medium with a randomly-inhomogeneous refraction index. It is shown that in the case of the gravitation wave field the phase shift of an electromagnetic wave does not increase with distance. The capability of space radio interferometry to detect relic gravitational waves as well as gravitational wave bursts of non cosmological origin are analyzed. (author). 64 refs, 2 figs