Black hole atom as a dark matter particle candidate

We propose the new dark matter particle candidate - the "black hole atom", which is an atom with the charged black hole as an atomic nucleus and electrons in the bound internal quantum states. As a simplified model we consider the the central Reissner-Nordstrom black hole with the electric charge neutralized by the internal electrons in bound quantum states. For the external observers these objects would look like the electrically neutral Schwarzschild black holes. We suppose the prolific production of black hole atoms under specific conditions in the early universe.Comment: 5 pages, 1 figures, with additional reference

Observational signatures of the giant planets collisions

We consider observational signatures of the collisions and partial destructions of giant exoplanets at the chaotic stage of the planetary systems evolution. The rate of these collisions in the Galaxy is estimated to be ~0.01-1 per yr. In the inelastic collision with a small relative velocity and small impact parameter, the planets may sufficiently lose their kinetic energy and merge together. Otherwise, if the planet is experienced a shallow tangential collision, it flews safety away. At the same time, the planets loss some part of their gas envelopes during mutual collisions. Collisions of the giant planets must be accompanied also by the radiation of energy from the radio to optical bands. The optical and near UV flashes result from the collision heating of the planet surface layers. Additionally, the collision compression and collapse of the powerful magnetosphere of giant planets are possible, with a successive generation of the radio bursts. According to our estimations, the corresponding rate the radio bursts is ~0.01-1 bursts per year with the maximum spectral flux ~30mJy at the frequencies ~3GHz and with a duration of the each burst ~1.5 hours. These signals are available for registration by the existing radio telescopes.Comment: 6 pages, 3 figures, preprint submitted to PS

GRB Redshift Distribution is Consistent with GRB Origin in Evolved Galactic Nuclei

Recently we have elaborated a new cosmological model of gamma-ray burst (GRB) origin (1998, ApJ 502, 192), which employs the dynamical evolution of central dense stellar clusters in the galactic nuclei. Those clusters inevitably contain a large fraction of compact stellar remnants (CSRs), such as neutron stars (NSs) and stellar mass black holes (BHs), and close encounters between them result in radiative captures into short-living binaries, with subsequent merging of the components, thereby producing GRBs (typically at large distances from the nucleus). In the present paper, we calculate the redshift distribution of the rate of GRBs produced by close encounters of NSs in distant galactic nuclei. To this end, the following steps are undertaken: (i) we establish a connection between the parameters of the fast evolving central stellar clusters (i.e. those for which the time of dynamical evolution exceeds the age of the Universe) with masses of the forming central supermassive black holes (SMBHs) using a dynamical evolution model; (ii) we connect these masses with the inferred mass distributions of SMBHs in the galactic nuclei and the redshift distribution of quasars by assuming a certain `Eddington luminosity phase' in their activity; (iii) we incorporate available observational data on the redshift distribution of quasars as well as a recently found correlation between the masses of galaxies and their central SMBHs. The resulting redshift distribution of the GRB rate, which accounts for both fast and slowly evolving galactic nuclei is consistent with that inferred from the BATSE data if the fraction of fast evolving galactic nuclei is in the range $0.016-0.16$.Comment: LaTeX, 4 pages (incl. 1 figure), to appear in "After the Dark Ages: When Galaxies Were Young (the Universe at 2<z<5)", eds. S.S. Holt and E.P. Smit

Destruction of axion miniclusters in the Galaxy

Previously, it has been established that axion dark matter (DM) is clustered to form clumps (axion miniclusters) with masses $M\sim10^{-12}M_\odot$. The passages of such clumps through the Earth are very rare events occurring once in $10^5$ years. It has also been shown that the Earth's passage through DM streams, which are the remnants of clumps destroyed by tidal gravitational forces from Galactic stars, is a much more probable event occurring once in several years. In this paper we have performed details calculations of the destruction of miniclusters by taking into account their distribution in orbits in the Galactic halo. We have investigated two DM halo models, the Navarro-Frenk-White and isothermal density profiles. Apart from the Galactic disk stars, we have also taken into account the halo and bulge stars. We show that about 2-5% of the axion miniclusters are destroyed when passing near stars and transform into axion streams, while the clump destruction efficiency depends on the DM halo model. The expected detection rate of streams with an overdensity exceeding an order of magnitude is 1-2 in 20 years. The possibility of detecting streams by their tidal gravitational effect on gravitational-wave interferometers is also considered.Comment: 9 pages, 3 figure