Search

Additional high-frequency components of the pulsar radiation in Crab Nebula are considered as a result of the resonance with the surface electromagnetic wave at nonlinear reflection from of the neutron star surface.This stimulated scattering consists in generation of a surface periodic relief by an incident field and diffraction on that relief the radiation of relativistic positrons, which fly from the magnetosphere to the star in the accelerating electric field of a polar gap., Comment: 6 pages, 2 figures; The Report on the Conference "PLASMA ELECTRONICS AND NEW ACCELERATION METHODS" 27-31 August 2018, Kharkov, Ukraine. We have added some figures, refs, footnotes and clarified some notation in the text

Gravlenses are efficiently explored for detecting the most distant galaxies (up to z=10 redshifts). As an example of the role played by gravlenses we refer to the observation of the galaxy merger at z=3 (Borys, et al; Berciano Alba, et al). We derived solutions for the Smoluchowski kinetic equation for the mass function of galaxies, which describes mergers in differential approximation (minor mergers). It is shown that the evolution of the slope of luminosity function observed in the Ultra Deep Hubble Field (Bouwence et al) can be described as a result of explosive evolution driven by galaxy mergers., Comment: 7 pages, 2 Postscript figures, The Report on the International Conference Electromagnetic Methods of Environmental Studies EMES-2012 deducated to memory of prof. Pavel Victorovich Bliokh, Kharkov, Ukraine, 2012. Abstracts, pp. 160-162

We derived solutions for the Smoluchowski kinetic equation for the mass function of galaxies, which describes mergers in differential approximation, where mergers with low-mass galaxies are the dominant factor. The evolution of the initial distribution is analyzed as well as the influence of the source represented by galaxies (halos) that separate from the global cosmological expansion. It is shown that the evolution of the slope of the power-law part of the luminosity function at a constant mass-to-luminosity ratio observed in the Ultra Deep Hubble Field can be described as a result of explosive evolution driven by galaxy mergers. In this case the exponent depends exclusively on the uniformity degree of merger probability as a function of mass., Comment: 25 pages, 5 Postscript figures; The Report on the International Conference "Astroparticle Physics, Gravitation and Cosmology", Kyiv, Ukraine, 2012. Book of Abstracts, p. 14. Published in Astrophysical Bulletin, 2013, Volume 68, Issue 3

The analytical expression for frequency of the maximum of radio emission intensity in pulsars with free electron emission from the stellar surface has been found. We have explained the correlation, known from observations, between the high-frequency cut-off and low-frequency turnover in radio emission spectrum of the pulsars. The explanation is based on peculiarities of electron acceleration in the inner polar gap, which we have analyzed., Comment: 12 pages, 3 figures; The Report on the Russian Conference "Modern Problems for Extragalactic Astronomy", Pushchino, Russia, 2012; Accepted for publication in JETP

Pulsars are the fast rotating neutron stars with strong magnetic field, that emit over a wide frequency range. In spite of the efforts during 40 years after the discovery of pulsars, the mechanism of their radio emission remains to be unknown so far. We propose a new approach to solving this problem for a subset of pulsars with a high-frequency cutoff of the spectrum from the Pushchino catalogue (the "Pushchino" sample). We provide a theoretical explanation of the observed dependence of the high-frequency cutoff from the pulsar period. The dependence of the cutoff position from the magnetic field is predicted. This explanation is based on a new mechanism for electron radio emission in pulsars. Namely, radiation occurs in the inner (polar) gap, when electrons are accelerated in the electric field that is increasing from zero level at the star surface. In this case acceleration of electrons passes through a maximum and goes to zero when the electron velocity approaches the speed of light. All the radiated power is located within the radio frequency band. The averaging of intensity radiation over the polar cap, with some natural assumptions of the coherence of the radiation, leads to the observed spectra. It also leads to an acceptable estimate of the power of radio emission., Comment: 9 pages, 5 Postscript figures; The Report on the International Conference on Physics of Neutron Stars, Saint-Petersburg, Russia, 2011. Book of Abstracts, p. 75. The text has been revised in accordance with the reviewer's comments. Published in Astrophysics and Space Science Volume 345, Issue 1 (2013), Page 169-175 http://www.springerlink.com

A wide range of events observed at the giant pulses (high energy density, observed localization of giant pulses (GPs) relative to the average pulse, fine structure of GPs with duration up to some nanoseconds, observed circular polarization of GPs, correlation between the GP phase and the phase of the hard pulsar emission X-ray and gamma) can be explained from the viewpoint that the internal polar gap is a cavity-resonator stimulated by discharges and radiating through the breaks in the magnetosphere. The new results in this field [the electromagnetic (em) waves generation in the gap in the process of longitudinal acceleration in the electric field vanishing on the star surface, high frequency break in the spectrum as a result of switching off this generation, formation in this process a power-low spectrum with a high frequency (hf) break, the possibility determination of pulsar magnetic field by the hf break position, the difference between main pulse and inter pulse mechanism generation, quantization of em tornado rotation in the gap and appearance of the bands in the inter pulse spectrum, influence the high energy density in the gap on pair generation and position of the dead line in pulsars] are added in the intermediate epilogue., Comment: 14 pages, 2 Postscript figures; added Appendix D (Intermediate Epilogue) with 20 references. The 8th International Conference on Physics of Neutron Stars in Saint-Petersburg,2008. Printed in Journal of Physical Science and Application 5 (2015) 48-60

The solution for the electromagnetic tornado in a vacuum gap of a pulsar that could serve as an explanation of the observed circular polarization of giant pulses from pulsars and might also explain the frequency strips observed in giant pulses spectrum is found., Comment: 4 pages, 3 Postscript figures; The fifth International conference Solitons, collapses and turbulence: achivement, developments and perspectives, dedicated to the 70-th anniversary of Professor Vladimir Zakharov, ed. E.A.Kuznetsov, Chernogolovka: ITP RAS, p.24 (2009)

The model of pulsar radio emission is discussed in which a coherent radio emis-sion is excited in a vacuum gap above polar cap of neutron star. Pulsar X and gamma radiation are considered as the result of low-frequency radio emission inverse Comp-ton scattering on ultra relativistic electrons accelerated in the gap. The influence of the pulsar magnetic field on Compton scattering is taken into account. The relation of radio and gamma radiation spectra has been found in the framework of the model., Comment: 15 pages, 3 figures, Russian version accepted to JETP, partly published in JETP Letters, Vol. 85, #6 (2007)

Radio images of supernova remnants in the framework of diffusion model are discussed. The distribution profiles of synchrotron radiation intensity for spherical injection source of relativistic electrons are reduced at different frequencies. An explanation of the observational data obtained on UTR-2, according to which the size of the supernova remnant at decametric waves is larger than the remnant size at high frequencies, is given., Comment: Published in Proceedings of the 14th Young Scientists Conference on Astronomy and Space Physics, Kyiv, Ukraine, April 23-28, 2007

We found equilibrium conditions for a self-gravitating toroidal vortex by taking into account thermal pressure. These conditions are shown to significantly differ from those for a disk and a sphere. The evolution of a thin vortex turns it into a compact vortex that loses mechanical stability for low masses at a polytropic index $\gamma < 4/3$ but retains stability for sufficiently high masses and densities determined by the velocity circulation in the vortex., Comment: 11 pages, 4 figures

The evolution and collapse of a gaseous toroidal vortex under the action of self-gravitation are considered using the Hamiltonian mechanics approach. It is shown that evolution occurs in three main stages separated by characteristic time scales. First, a compression along the small radius to a quasi-equilibrium state takes place, followed by a slower compression along the large radius to a more stable compact vortex object. In the latter stage, the possibility of effective scattering and ejection of particles along the vortex axis (jet formation) is detected. As a result, mass, energy, and momentum losses take place, and the vortex collapses., Comment: 11 pages, 3 figures

In the framework of the Kompaneets approximation the propagation of a shock front (SF) in inhomogeneous medium with the power-law density decrease at the exponent $n=2$ is investigated. For this important case corresponding to outer regions of the solar and stellar coronas an unexpectedly simple exact solution clearing a structure of the general solution for an arbitrary monotonic density of medium is found. Our results for plane-layered medium are compared to the Korycansky one for off-centre explosion in radially stratified medium. The relation between the solutions in these media are found and a new exact solution for a noncentral explosion in the case of density singularity on the finite radius is received., Comment: LaTeX, 18 pages, 3 figures (4 Postscript files)

Connection between the quasar luminosity function and galaxy mass function is investigated in the framework of a phenomenological approach which relates AGN formation to galaxy mergers. Quasars are assumed to be short-lived, the luminosity of a quasar is controlled by the masses and angular momenta of the merged galaxies which have formed the quasar, and the amount of gas in them (the masses and momenta determine the quantity of mass which loses its angular momentum and can fall to the center). The proposed model can explain the shape and evolution of the quasar luminosity function, and allows us to estimate the parameters: the fraction of matter which falls into the center $\eta$ (which seems to be related to the quantity of gas in the galaxies) and $\kappa$ (an average density contrast in the regions where quasars form). The obtained values of $\kappa$ vary from $\sim 4--7$ at $z=0.5$ to $\sim 1--2$ at $z=2$, $\eta$ vary from a few per cent at $z=0.5$ to a few tens per cent or even values close to 1 at $z=2$. In contrast to the cases considered earlier by the authors, the Eddington limit which, probably, can be exceeded in quasars plays an essential role., Comment: LaTeX2e, PicTeX, 15 pages

A Monte Carlo simulation of mergers in clusters of galaxies is carried out. An ``explosive'' character of the merging process (an analog of phase transition), suggested earlier by Cavaliere et al. (1991), Kontorovich et al. (1992), is confirmed. In particular, a giant object similar to cD-galaxy is formed in a comparatively short time as a result of mergers. Mass and angular momentum distribution function for galaxies is calculated. An intermediate asymptotics of the mass function is close to a power law with the exponent $\alpha\approx2$. It may correspond to recent observational data for steep faint end of the luminosity function. The angular momentum distribution formed by mergers is close to Gaussian, the rms dimensionless angular momentum $S/(GM^3R)^{1/2}$ being approximately independent of mass, which is in accordance with observational data., Comment: 10 pages, LaTeX 2.09, PicTeX. Uses l-aa.sty, prepictex.tex, pictex.tex, postpictex.tex. Inserts four external PostScript files. To appear in Astronomy and Astrophysics