On particle collisions in the gravitational field of the Kerr black hole

Scattering of particles in the gravitational field of Kerr black holes is considered. It is shown that scattering energy of particles in the centre of mass system can obtain very large values not only for extremal black holes but also for nonextremal ones existing in Nature. This can be used for explanation of still unresolved problem of the origin of ultrahigh energy cosmic rays observed in Auger experiment. Extraction of energy after the collision is investigated. It is shown that due to the Penrose process the energy of the particle escaping the hole at infinity can be large. Contradictions in the problem of getting high energetic particles escaping the black hole are resolved.Comment: LaTeX, 7 pages, 2 figure

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

Back reaction of the gravitational radiation on the metric of spacetime

The problem of back reaction of the gravitational radiation of the two merging black holes on the metric of the spacetime is investigated. It is shown for some models that large energy density of the gravitational waves close to the merger can lead to the disappearance of the visible accretion disc of the merged pair of black holes.Comment: 9 pages, no figures. New version matches the published version, includes adding references and corrections mainly in section