Active Galactic Nuclei and Transformation of Dark Matter into Visible Matter

The hypothesis that dark matter is converted into visible particles in active galactic nuclei is investigated. If dark matter consists of stable superheavy neutral particles and active galactic nuclei are rotating black holes, then, due to the Penrose process, superheavy particles can decay into unstable particles with larger mass, whose decay into quarks and leptons leads to events in cosmic rays observed by the Auger group. Similar processes of decay of superheavy particles of dark matter into visible matter occurred in the early Universe. Numerical estimates of the processes in active galactic nuclei and in the early Universe are given.Comment: 5 pages, LaTeX; v2: one reference added, published versio

Interactions of oblique interplanetary discontinuities and their manifestations during STIP intervals 15-19

The generation of slow shock waves as the result of the interaction of Alfven discontinuities with solar wind contact surfaces is considered. The latter are taken to be the boundaries of proton and alpha-particle concentration inhomogeneities. It is found that the intensity of the Alfven discontinuity may be increased as the result of its interaction with the more dense plasma. The converse (i.e., decrease of the Alfven discontinuity's intensity following interaction with a less dense plasma) is also indicated. Also discussed is the generation of a magnetic cloud as the result of the interaction of a quasi-parallel Alfven discontinuity with a dense plasma contact surface. It is shown that the (solar-generated) Alfven discontinuity may then be transformed into non-flare fast and slow shock waves as the result of this interaction. Thus, it is indicated that some fast shock waves in the solar wind may have a nonsolar origin

Particles with negative energies in black holes

The problem of the existence of particles with negative energies inside and outside of Schwarzschild, charged and rotating black holes is investigated. Different definitions of the energy of the particle inside the Schwarzschild black hole are analyzed and it is shown in what cases this energy can be negative. A comparison is made for the cases of rotating black holes described by the Kerr metric when the energy of the particle can be negative in the ergosphere and the Reissner-Nordstrom metric.Comment: 10 pages, 2 figures, typos correction to match published versio

On collisions with unlimited energies in the vicinity of Kerr and Schwarzschild black hole horizons

Two particle collisions close to the horizon of the rotating nonextremal Kerr's and Schwarzschild black holes are analyzed. For the case of multiple collisions it is shown that high energy in the centre of mass frame occurs due to a great relative velocity of two particles and a large Lorentz factor. The dependence of the relative velocity on the distance to horizon is analyzed, the time of movement from the point in the accretion disc to the point of scattering with large energy as well as the time of back movement to the Earth are calculated. It is shown that they have reasonable order.Comment: 6 pages, 1 figure. arXiv admin note: significant text overlap with arXiv:1105.154

Space-Time Description of Scalar Particle Creation by a Homogeneous Isotropic Gravitational Field

We give the generalization of the method of the space-time description of particle creation by a gravitational field for a scalar field with nonconformal coupling to the curvature. The space-time correlation function is obtained for a created pair of the quasi-particles, corresponding to a diagonal form of the instantaneous Hamiltonian. The case of an adiabatic change of the metric of homogeneous isotropic space is analyzed. We show that the created pairs of quasi-particles in de Sitter space should be interpreted as pairs of virtual particles.Comment: 7 pages, 3 figure

Hamiltonian approach to the dynamical Casimir effect

A Hamiltonian approach is introduced in order to address some severe problems associated with the physical description of the dynamical Casimir effect at all times. For simplicity, the case of a neutral scalar field in a one-dimensional cavity with partially transmitting mirrors (an essential proviso) is considered, but the method can be extended to fields of any kind and higher dimensions. The motional force calculated in our approach contains a reactive term --proportional to the mirrors' acceleration-- which is fundamental in order to obtain (quasi)particles with a positive energy all the time during the movement of the mirrors --while always satisfying the energy conservation law. Comparisons with other approaches and a careful analysis of the interrelations among the different results previously obtained in the literature are carried out.Comment: 4 pages, no figures; version published in Phys. Rev. Lett. 97 (2006) 13040

The speed of gravity in general relativity

The question is discussed of what is the speed of gravity (at the fundamental non-perturbative level). The question is important, if nowhere else, in discussing the problem of information "lost" in black holes. It turns out that the duly defined "gravitational signal" generally may be causal, superluminal and "semi-superluminal". In the class of globally hyperbolic spacetimes the two last varieties coincide. And if some (often imposed, but not always satisfied) conditions hold, the signals may be \emph{only} causal. In this sense the speed of gravity does not exceed the speed of light.Comment: typos corrected, et

Graphene tests of Klein phenomena

Graphene is characterized by chiral electronic excitations. As such it provides a perfect testing ground for the production of Klein pairs (electron/holes). If confirmed, the standard results for barrier phenomena must be reconsidered with, as a byproduct, the accumulation within the barrier of holes.Comment: 8 page

Spontaneous symmetry breaking for long-wave gravitons in the early Universe

It is shown that nonlinear terms in equations of gravitons on the background of curved space-time of the expanding Universe can solve the problem of the negative square of the effective mass formally arising in linear approximation for gravitons. Similar to well known spontaneous breaking of symmetry in Goldstone model one must take another vacuum so that nonzero vacuum expectation value of the quantized graviton field leads to change of spectrum for gravitons. There appears two graviton fields, one with the positive mass, another with the zero mass. Energy density and the density of particles created by gravitation of the expanding Universe are calculated for some special cases of the scale factor. Numerical results are obtained for the dust universe case.Comment: 13 page