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We investigate the gravitational lensing effect in presence of plasma. We observe that in a homogeneous plasma the gravitational deflection angle differs from that in vacuum, and it depends on the frequency of the photon. We discuss observational consequences of this dependence for the point-mass lensing and estimate possibility of the observation of this effect by the planned project Radioastron. [ABSTRACT FROM AUTHOR]

Results of 2D simulations of magnetorotational(MR) mechanism of core collapse supernova explosions are discussed. Nonuniform collapse of rotating core leads to differential rotation of the core. The differential rotation and initial poloidal magnetic field results in appearance of toroidal component of the magnetic field and its growth with time. Increased magnetic pressure leads to the formation of a compression wave which moves outwards. It transforms into the fast MHD shock wave (supernova shock wave). The shape of the MR supernova explosion qualitatively depends on the configuration of the initial magnetic field. For a dipole-like initial magnetic field the supernova explosion develops mainly along the rotational axis forming a mildly collimated jet. Quadrupole-like initial magnetic field leads to the explosion developing mainly along equatorial plane. The magnetorotational instability(MRI) was found in our simulations. MRI results in exponential growth of all components of the magnetic field. The supernova explosion energy grows with an increase of the initial core mass and rotational energy of the core, and corresponds to the observational data. Special features and difficulties of 3D simulations of magnetorotational supernova explosions are discussed. [ABSTRACT FROM AUTHOR]

We propose a physical model of the X-ray emitting region of the Galactic microquasar SS433 that includes thermal emission from the accretion disk, jets and hot corona where the photons of different origin are comptonized. We have employed a Monte-Carlo technique to calculate X-ray continuum spectra of comptonized thermal plasma and applied it to describe the broadband X-ray continuum of SS433 observed by INTEGRAL. From comparison with INTEGRAL observations, we estimate physical parameters of the X-ray emitting region in SS433 and present model spectra for different viewing angles of the object. [ABSTRACT FROM AUTHOR]

Results of the magnetorotational explosion simulations are presented for differentially rotating magnetized cloud. Differential rotation leads to the amplification of the toroidal component of the magnetic field. The part of the rotational energy of the cloud is transformed to the kinetic energy of the radial motion. Part of the matter ~ 7% of the mass of the cloud (3.3% of the final gravitational energy of the cloud) gets radial kinetic energy which is larger than its potential energy and can be thrown away to the infinity, This part of the cloud carries about 30% of the initial angular momentum of the cloud. For the simulations we used specially developed completely conservative implicit 2D Lagrangian scheme on triangular grid with grid reconstruction. [ABSTRACT FROM AUTHOR]

Jet formation is connected most probably with matter acceleration from the vicinity of rotating magnetized bodies. It is usually related to the mass outflows and ejection from accretion disks around black holes. Problem of jet collimation is discussed. Collapse of a rotating magnetized body during star formation or supernovae explosion may lead to a jet-like mass ejection for certain angular velocity and magnetic field distributions at the beginning of the collapse. Jet formation during magnetorotational explosion is discussed basing on the numerical simulation of collapse of magnetized bodied with quasi-dipole field. [ABSTRACT FROM AUTHOR]

The present common view abour GRB origin is related to cosmology. There are two evidences in favour of this interpretation. The first is connected with statistics, the second is based on measurements of the redshifts in the GRB optical afterglows. Red shifts in optical afterglows had been observed only in long GRB. Statistical errors, and possibility of galactic origin of short GRB is discussed; their connection with Soft Gamma Repeators (SGR) is analyzed. [ABSTRACT FROM AUTHOR]

Approximate method for investigating stellar stability in GR is presented. It is based on the approximate Galerkin method. Spectral Galerkin method is widely used in numerical simulations. The development of the method is based on a generalization of the well-known energetic method. In full GR treatment it results in more simple equations of the stability than in standard perturbation approach. [ABSTRACT FROM AUTHOR]