A. N. Aliev

Gravitational Aharonov-Bohm radiation in string-generated conical space-time

Abstract The scalar, electromagnetic, and gravitational radiation in conical space-time generated by an infinite straight cosmic string is considered. It is shown that freely moving particles in conical space emit radiation. Though there is no local force acting upon particles, radiation arises due to the topological properties of space-time and it can be interpreted as the radiative gravitational Aharonov-Bohm effect. The string-modified magnetobremsstrahlung is also discussed.

Exact solutions for magnetized black holes

The Ernst-Wild solution with conical singularities removed is discussed. The physical quantities characterizing the modified solution including electromagnetic four-potential, electric, and magnetic field fluxes through the upper hemisphere of the horizon, equatorial and meridional circumferences on the horizon are calculated.

Negative absorption near a magnetized black hole: Black hole masers

The mechanism of the energy extraction from charged particles moving in the vicinity of black holes due to the negative absorption of electromagnetic waves is considered. It is shown that there exist a number of resonant frequencies for which the ring of particles circling in the equatorial plane of Kerr black holes amplifies the incident electromagnetic waves. The negative absorption coefficients are calculated both for non-relativistic and ultrarelativistic cases.

On the observability of the magnetic precession of the black hole accretion disks

The precession of a rotating charged black hole in an external magnetic field is considered. The possibility of observing the effect in black hole systems with magnetized accretion, disks is discussed.

Energetics of magnetized black holes: Effective ergospheres and superradiance

The model of a black hole rotating in an external magnetic field is considered. The mechanisms of the energy extraction from the black hole in terms of the effective ergospheres for charged particles are described. It is shown that the external magnetic field essentially influences the boundaries of the effective ergospheres and the superradiance threshold.

Synchrotron radiation in curved space—time

Synchrotron emission by ultrarelativistic particles moving in a magnetic field in curved space-time is examined by the method of local coordinates. Generally covariant equations are obtained for the radiation spectrum in the classical and quantum cases. It is shown that the relative magnitude of the quantum corrections to the radiation spectrum increases with particle motion near the event horizon in the Kerr metric. The limit of geodesic synchrotron radiation is examined.

Physical interpretation of the Kerr-Newman-Ernst solutions

A relation is determined between the physical quantities in the Kerr-Newman priming solution and the Kerr-Newman-Ernst solution transformed by using the Harrison solution. It is shown that this latter possesses a nonsingular horizon of events. The values obtained for the 4-potential of the electromagnetic field of the transformed solution is in a linear approximation in the magnetic field intensity.

Black hole in an asymmetric electromagnetic field: New ponderomotive effects — Spin precession and drift

Abstract Two new ponderomotive effects in black hole physics are indicated: (i) the precession of the rotation axis of a charged black hole in an external magnetic field, (ii) the drift of a non-charged rotating hole in an asymmetric homogeneous electromagnetic field posessing a non-zero Poynting vector. The precession time for a black hole of solar mass with Q = 10 −5 M in a magnetic field B ∼ 10 12 G is about a year.