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Search Results: 1 - 10 of 238944 matches for " E. I. Sorokina "
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UV Light Curves of Thermonuclear Supernovae
S. I. Blinnikov,E. I. Sorokina
Physics , 2000,
Abstract: Ultraviolet light curves are calculated for several thermonuclear supernova models using a multifrequency radiation hydrodynamic code. It is found that Chandrasekhar-mass models produce very similar light curves both for detonation and deflagration. Sub-Chandrasekhar-mass models essentially differ from ``normal'' Chandrasekhar ones regarding behaviour of their UV fluxes. Differences in absolute brightness and in shape of light curves of thermonuclear supernovae could be detectable up to 300 Mpc with modern UV space telescopes.
Energy exchange inside SN ejecta and light curves of SNe Ia
E. I. Sorokina,S. I. Blinnikov
Physics , 2002,
Abstract: A treatment of line opacity in expanding medium is most crucial for the light curve (LC) modeling of Type Ia supernovae (SNe Ia). Spectral lines are the main source of opacity inside SN Ia ejecta from ultraviolet through infrared range. Here we focus on the mean opacity for the energy equation. We solve the Boltzmann equation for photons in the comoving frame for a spherically-symmetrical flow. For rectangle line profiles we find an analytical expression for frequency averaged intensity and absorptive opacity. The results differ from previously known heuristic solutions. The LCs in the I-band are in better agreement with observations.
Supernova Explosions inside Carbon-Oxygen Circumstellar Shells
S. I. Blinnikov,E. I. Sorokina
Physics , 2010,
Abstract: Motivated by a recent discovery of Supernova 2010gx and numerical results of Fryer et al.(2010), we simulate light curves for several type I supernova models, enshrouded by dense circumstellar shells, or "super-wind", rich in carbon and oxygen and having no hydrogen. We demonstrate that the most luminous events like SN2010gx can be explained by those models at moderate explosion energies (2-3) foe if the total mass of SN ejecta and a shell is (3-5) Msun and the radius of the shell is ~10^{16} cm.
Thermonuclear Burning Regimes and the Use of SNe Ia in Cosmology
E. I. Sorokina,S. I. Blinnikov,O. S. Bartunov
Physics , 1999, DOI: 10.1134/1.20370
Abstract: The calculations of the light curves of thermonuclear supernovae are carried out by a method of multi-group radiation hydrodynamics. The effects of spectral lines and expansion opacity are taken into account. The predictions for UBVI fluxes are given. The values of rise time for B and V bands found in our calculations are in good agreement with the observed values. We explain why our results for the rise time have more solid physical justification than those obtained by other authors. It is shown that small variations in the chemical composition of the ejecta, produced in the explosions with different regimes of nuclear burning, can influence drastically the light curve decline in the B band and, to a lesser extent, in the V band. We argue that recent results on positive cosmological constant Lambda, found from the high redshift supernova observations, could be wrong in the case of possible variations of the preferred mode of nuclear burning in the earlier Universe.
Development prospects and stability limits of the mid-IR Kerr-lens mode-locked lasers
V. L. Kalashnikov,E. Sorokin,I. T. Sorokina
Physics , 2002,
Abstract: The Kerr-lens mode locking ability and the ultrashort pulse characteristics are analyzed numerically for the Cr-doped ZnTe, ZnSe, ZnS active media. The advantages of these materials for the femtosecond lasing within 2 - 3 $\mu$m spectral range are demonstrated.
Spectral Characteristics of Ultrashort Pulses in Kerr-lens Mode-Locked Lasers
V. L. Kalashnikov,E. Sorokin,I. T. Sorokina
Physics , 2000,
Abstract: A number of factors that influence spectral position of the femtosecond pulse in a Kerr-lens modelocked Cr:LiSGaF laser have been identified: high-order dispersion, gain saturation, reabsorption from the ground state, and stimulated Raman scattering. Using the one-dimensional numerical model for the simulation of the laser cavity, the relative contributions of different factors have been compared. The Raman effect provides the largest self-frequency shift from the gain peak (up to 60 nm), followed by the gain saturation (25 nm), while the high-order dispersion contribution is insignificant (5 nm). Comparison with the experimental data confirm that the stimulated Raman scattering is a main cause of the ultrashort pulse self-frequency shift observed in Cr:LiSGaF and Cr:LiSAF lasers
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.
Shock breakouts in SNe Ib/c
S. I. Blinnikov,D. K. Nadyozhin,S. E. Woosley,E. I. Sorokina
Physics , 2002,
Abstract: Numerical modeling of shock breakout in compact presupernovae of type Ib/c is done by two independent methods. Peak color temperatures reach 4 to 8 million K for explosion energies 1 to 9 foe with a typical local time-scale of 0.03 seconds. In the obverver's frame the burst is smeared over few seconds due to light travel time correction R/c.
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