Alexander Shatskiy

Astrophysics of Wormholes

We consider the hypothesis that some active galactic nuclei and other compact astrophysical objects may be current or former entrances to wormholes (WHs). A broad mass spectrum for astrophysical WHs is possible. We consider various new models of the static WHs including WHs maintained mainly by an electromagnetic field. We also discuss observational effects of a single entrance to WH and a model for a binary astrophysical system formed by the entrances of WHs with magnetic fields and consider its possible manifestation.

PASSAGE OF RADIATION THROUGH WORMHOLES

We investigate numerically the process of the passage of a radiation pulse through a wormhole and the subsequent evolution of the wormhole that is caused by the gravitational action of this pulse. The initial static wormhole is modeled by a spherically symmetrical solution with zero mass. The radiation pulses are modeled by spherically symmetrical shells of self-gravitating massless scalar fields. We demonstrate that the compact signal propagates through the wormhole and investigate the dynamics of the fields in this process for both cases: collapse of the wormhole into the black hole and for the expanding wormhole.

Physics of the interior of a black hole with an exotic scalar matter

We use a numerical code to consider the nonlinear processes arising when a Reissner-Nordstroem black hole is irradiated by an exotic scalar field ( modeled as a free massless scalar field with an opposite sign for its energy-momentum tensor). These processes are quite different from the processes arising in the case of the same black hole being irradiated by a pulse of a normal scalar field. In our case, we did not observe the creation of a spacelike strong singularity in the T region of the space-time. We investigate the antifocusing effects in the gravity field of the exotic scalar field with the negative energy density and the evolution of the mass function. We demonstrate the process of the vanishing of the black hole when it is irradiated by a strong pulse of an exotic scalar field.

Stability analysis of a Morris-Thorne-Bronnikov-Ellis wormhole with pressure

The model of a spherical Morris-Thorne-Bronnikov-Ellis wormhole is analyzed for stability. The matter of this wormhole is composed of a radial monopole magnetic field and a quasi-perfect phantom fluid. In the stationary case, the energy density of this fluid is negative and equal in magnitude to twice the energy density of the magnetic field. There is no pressure of this fluid in the stationary case (phantom dust), while in the case where the fluid energy density deviates from its stationary value, the pressure is proportional to the deviation of the energy density from its stationary value. An example of a wormhole stable against radial perturbations has been obtained.

Non-singular Brans-Dicke cosmology with cosmological constant

We consider Brans-Dicke cosmology with cosmological constant with negative w parameter and an arbitrary (in general non-vanishing) scale factor at the Big Bang. The field equations describe the flat universe, current observational values for Hubble constant H and deceleration parameter q play a role of initial conditions. In order to solve field equations we adopt the approach of Uehara and Kim (1982). They considered only positive values of w, hence our solution is a new one and has not been described in their paper. Our main result is that unlike the standard cosmology the scale factor may not vanish in its evolution back in time. In other words our model displays a cosmological bounce and avoids the initial singularity. The formula for the scale factor, leading to the bounce, is only valid for the dust-filled universe and hence cannot be adequate for the hot stage in the early universe when the bounce happens. So, the results of this paper are only qualitative in nature and must be used to obtain initial values for the hot stage of the unverse when one considers the evolution back in time.We discuss a Brans-Dicke model with a cosmological constant, a negative value of the

Accretion of exotic matter onto a Reissner-Nordström black hole

w

A multi-element cosmological model with a complex space-time topology

parameter, and an arbitrary (in general nonvanishing) scale factor at the big bang. The Friedmann equations for a flat universe are considered. The current observational values for Hubble constant

Observational effects in black and white holes (dynamical wormholes)

{H}_{0}

Spectrum of relativistic radiation from electric charges and dipoles as they fall freely into a black hole

and deceleration parameter

A new method for reconstructing the density distribution of matter in the disks of spiral galaxies from the rotation velocity curve in it

{q}_{0}