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Search Results: 1 - 10 of 262304 matches for " D. I. Kosenko "
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Gamma-Ray Bursts and TeV quantum gravity
K. A. Postnov,D. I. Kosenko
Physics , 2002,
Abstract: Limitations on the multi-dimensional TeV-scale quantum gravity model by Arkani-Hamed, Dimopoulos and Dvali (1998) and on model by Dvali, Gabadadze, Porrati (2000) are obtained from an analysis of gamma-ray bursts at cosmological distances (relativistic fireball model).
Fluctuations of Gravitational Wave Noise from Unresolved Extragalactic Sources
D. I. Kosenko,K. A. Postnov
Physics , 1999,
Abstract: Angular fluctuations of stochastic gravitational wave backgrounds (GWB) produced by extragalactic astrophysical sources are calculated. The angular properties of such backgrounds are determined by the large scale structure of Universe (galaxy clustering). The evolution of star formation rate with redshift is taken into account. Fluctuations of the metric strain amplitude associated with such noises at angular scales of about one degree are found to be of order 5-20% slowly growing toward smaller angular scales. This feature can be potentially used to separate astrophysical GWB from cosmological ones in future experiments.
Modeling supernova remnants: effects of diffusive cosmic-ray acceleration on the evolution, application to observations
D. Kosenko,S. I. Blinnikov,J. Vink
Physics , 2011, DOI: 10.1051/0004-6361/201116630
Abstract: We present numerical models for supernova remnant evolution, using a new version of the hydrodynamical code SUPREMNA. We added cosmic ray diffusion equation to the code scheme, employing two-fluid approximation. We investigate the dynamics of the simulated supernova remnants with different values of cosmic ray acceleration efficiency and diffusion coefficient. We compare the numerical models with observational data of Tycho's and SN1006 supernova remnants. We find models which reproduce the observed locations of the blast wave, contact discontinuity, and reverse shock for the both remnants, thus allowing us to estimate the contribution of cosmic ray particles into total pressure and cosmic-ray energy losses in these supernova remnants. We derive that the energy losses due to cosmic rays escape in Tycho's supernova remnant are 10-20% of the kinetic energy flux and 20-50% in SN1006.
On the Gravitational Wave Noise from Unresolved Extragalactic Binaries
D. I. Kosenko,K. A. Postnov
Physics , 1998,
Abstract: We calculate stochastic gravitational wave background produced by extragalactic merging binary white dwarfs at the LISA frequencies $10^{-3}-10^{-2}$ Hz with account of a strong evolution of global star formation rate in the Universe recently established observationally. We show that for the observed global star formation history and modern cosmological models the extragalactic background is an order of magnitude smaller than the mean Galactic value. An early star formation burst at high redshifts can bring it at a higher level but still a few times lower than the mean Galactic one.
Time-dependent thermal effects in GRB afterglows
K. A. Postnov,S. I. Blinnikov,D. I. Kosenko,E. I. Sorokina
Physics , 2003, DOI: 10.1016/j.nuclphysbps.2004.04.059
Abstract: Time-dependent thermal effects should accompany standard non-thermal afterglows of GRB when gamma-rays pass through inhomogeneous surroundings of the GRB site. Thermal relaxation of an optically thin plasma is calculated using time-dependent collisional ionization of the plasma ion species. X-ray emission lines are similar to those found in the fading X-ray afterglow of GRB 011211. Thermal relaxation of clouds or shells around the GRB site could also contribute to the varying late optical GRB afterglows, such as in GRB021004 and GRB030329.
X-ray emission of young SN Ia remnants as a probe for an explosion model
D. I. Kosenko,E. I. Sorokina,S. I. Blinnikov,P. Lundqvist
Physics , 2002,
Abstract: We present results of hydrodynamical simulations of young supernova remnants. To model the ejecta, we use several models (discussed in literature) of type Ia supernova explosions with different abundances. Our hydro models are one-dimensional and spherically symmetrical, but they take into account ionization kinetics with all important processes. We include detailed calculations for the X-ray emission, allowing for time-dependent ionization and recombination. In particular, we compare the computed X-ray spectra with recent XMM-Newton observations of the Tycho SN remnant. Our goal is to find the most viable thermonuclear SN model that gives good fits to both these X-ray observations and typical SN Ia light curves.
Time-dependent thermal X-ray afterglows from GRBs
D. I. Kosenko,S. I. Blinnikov,K. A. Postnov,P. Lundqvist,E. I. Sorokina
Physics , 2002,
Abstract: Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.
Oxygen emission in remnants of thermonuclear supernovae as a probe for their progenitor system
D. Kosenko,W. Hillebrandt,M. Kromer,S. I. Blinnikov,R. Pakmor,J. S. Kaastra
Physics , 2014, DOI: 10.1093/mnras/stv348
Abstract: Recent progress in numerical simulations of thermonuclear supernova explosions brings up a unique opportunity in studying the progenitors of Type Ia supernovae. Coupling state-of-the-art explosion models with detailed hydrodynamical simulations of the supernova remnant evolution and the most up-to-date atomic data for X-ray emission calculations makes it possible to create realistic synthetic X-ray spectra for the supernova remnant phase. Comparing such spectra with high quality observations of supernova remnants could allow to constrain the explosion mechanism and the progenitor of the supernova. The present study focuses in particular on the oxygen emission line properties in young supernova remnants, since different explosion scenarios predict a different amount and distribution of this element. Analysis of the soft X-ray spectra from supernova remnants in the Large Magellanic Cloud and confrontation with remnant models for different explosion scenarios suggests that SNR 0509-67.5 could originate from a delayed detonation explosion and SNR 0519-69.0 from an oxygen-rich merger.
The resonance absorption probability function for neutron and multiplicative integral
V. D. Rusov,V. A. Tarasov,S. I. Kosenko,S. A. Chernegenko
Physics , 2012,
Abstract: The analytical approximations for the moderating neutrons flux density like Fermi spectra, widely used in reactor physics, involve the probability function for moderating neutron to avoid the resonant absorption obtained using some restrictive assumptions regarding the acceptable resonances width. By means of multiplicative integral (Volterra integral) theory for a commutative algebra an analytical expression for the probability function is obtained rigorously without any restrictive assumptions.
On the Fractal Mechanism of Interrelation Between the Genesis, Size and Composition of Atmospheric Particulate Matters in Different Regions of the Earth  [PDF]
Vitaliy D Rusov, Radomir Ilic, Radojko Jacimovic, Vladimir N Pavlovich, Yuriy A Bondarchuk, Vladimir N. Vaschenko, Tatiana N Zelentsova, Margarita E Beglaryan, Elena P Linnik, Vladimir P Smolyar, Sergey I Kosenko, Alla A Gudyma
Atmospheric and Climate Sciences (ACS) , 2011, DOI: 10.4236/acs.2011.13014
Abstract: Experimental data from the National Air Surveillance Network of Japan from 1974 to 1996 and from inde-pendent measurements performed simultaneously in the regions of Ljubljana (Slovenia), Odessa (Ukraine) and the Ukrainian “Academician Vernadsky” Antarctic station (64o15W; 65o15S), where the air elemental composition was determined by the standard method of atmospheric particulate matter (PM) collection on nucleopore filters and subsequent neutron activation analysis, were analyzed. Comparative analysis of dif-ferent pairs of atmospheric PM element concentration data sets, measured in different regions of the Earth, revealed a stable linear (on a logarithmic scale) correlation, showing a power law increase of every atmos-pheric PM element mass and simultaneously the cause of this increase – fractal nature of atmospheric PM genesis. Within the framework of multifractal geometry we show that the mass (volume) of atmospheric PM elemental components has a log normal distribution, which on a logarithmic scale with respect to the random variable (elemental component mass) is identical to normal distribution. This means that the parameters of two-dimensional normal distribution with respect to corresponding atmospheric PM-multifractal elemental components measured in different regions, are a priory connected by equations of direct and inverse linear regression, and the experimental manifestation of this fact is the linear correlation between the concentra-tions of the same elemental components in different sets of experimental atmospheric PM data.
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