A. A. Shatskii

The sky of a universe as seen through a wormhole

We consider a technique of calculating deflection of the light passing through wormholes (from one universe to another). We find fundamental and characteristic features of electromagnetic radiation passing through the wormholes. Making use of this, we propose new methods of observing distinctive differences between wormholes and other objects as well as methods of determining characteristic parameters for different wormhole models.

Einstein-Rosen bridges and the characteristic properties of gravitational lensing by them

It is shown that Einstein-Rosen bridges (wormholes)—hypothetical objects that topologically connect separate locations in the Universe—can be static solutions of the Einstein equations. The corresponding equations for bridges are reduced to a form convenient for their analysis and numerical solution. The matter forming the bridge must have a sufficiently hard and anisotropic equation of state. Our results are compared with a previously known analytic solution for a bridge, which is a special case of the general solution in the framework of general relativity. The deflection of photons by the bridge (gravitational lensing) is studied.It is shown that Einstein-Rosen bridges (wormholes)—hypothetical objects that topologically connect separate locations in the Universe—can be static solutions of the Einstein equations. The corresponding equations for bridges are reduced to a form convenient for their analysis and numerical solution. The matter forming the bridge must have a sufficiently hard and anisotropic equation of state. Our results are compared with a previously known analytic solution for a bridge, which is a special case of the general solution in the framework of general relativity. The deflection of photons by the bridge (gravitational lensing) is studied.

Semi-permeable wormholes and the stability of static wormholes

The stability of one type of the static Ellis-Bronnikov-Morris-Thorne wormholes is considered. These wormholes filled with radial magnetic field and phantom dust with a negative energy density.Physical processes arising when an impermeable wormhole is irradiated by self-gravitating, exotic radiation are considered. It is shown that, in this case, the conditions required for the passage of signals fromanother universe into our own arise only in our Universe, whereas signals cannot pass through the wormhole in the opposite direction. Such wormholes are called semi-permeable. The stability of a static wormhole filled with radial magnetic field and exotic dust with a negative energy density is also considered.

A new method for determining the masses of black holes

Characteristic properties of the electromagnetic spectrum of a dipole freely falling radially toward a Schwartzschild black hole are determined. These properties can be used to determined the mass of the black hole, as well as some characteristics of the magnetosphere or accretion disk surrounding the black hole.

Electric and magnetic fields in the astrophysics of wormholes

We consider the properties of electric and magnetic fields in vacuum in the neighborhood of static, spherically symmetric wormholes. Although certain aspects of this problem have been considered before, some important features remained undiscovered. We study in detail the properties of electric and magnetic fields in the case of quasi-adiabatic motion of field sources near an Ellis-Bronnikov wormhole and the passage of such sources through the wormhole. An exact solution is found in closed form for a wormhole immersed in a magnetic field that is homogeneous at infinity, as well as an exact solution for a dipolar field without sources. The properties of electromagnetic fields are important for possible observational manifestations of wormholes in astrophysics.

Is There a Relationship between the Density of Primordial Black Holes in a Galaxy and the Rate of Cosmological Gamma-Ray Bursts?

The rate of accretion of matter from a solar-type star onto a primordial black hole (PBH) that passes through it is calculated. The probability that a PBH is captured into an orbit around a star in a galaxy is found. The mean lifetime of the PBH in such an orbit and the rate of orbital captures of PBHs in the galaxy are calculated. It is shown that this rate does not depend on the mass of the PBH. This mechanism cannot make an appreciable contribution to the rate of observed gamma-ray bursts. The density of PBHs in the galaxy can reach a critical value—the density of the mass of dark matter in the galaxy.The rate of accretion of matter from a solar-type star onto a primordial black hole (PBH) that passes through it is calculated. The probability that a PBH is captured into an orbit around a star in a galaxy is found. The mean lifetime of the PBH in such an orbit and the rate of orbital captures of PBHs in the galaxy are calculated. It is shown that this rate does not depend on the mass of the PBH. This mechanism cannot make an appreciable contribution to the rate of observed gamma-ray bursts. The density of PBHs in the galaxy can reach a critical value the density of the mass of dark matter in the galaxy.