Lightcurves of thermonuclear supernovae as a probe of the explosion mechanism and their use in cosmology

Thermonuclear supernovae are valuable for cosmology but their physics is not yet fully understood. Modeling the development and propagation of nuclear flame is complicated by numerous instabilities. The predictions of supernova light curves still involve some simplifying assumptions, but one can use the comparison of the computed fluxes with observations to constrain the explosion mechanism. In spite of great progress in recent years, a number of issues remains unsolved both in flame physics and light curve modeling.Comment: 9 pages, 2 figures; presented at the 3rd Sakharov Conference (Moscow, June 2002) and at the 4th Workshop "New Worlds in Astroparticle Physic" (Faro, Portugal, September 2002

UV Light Curves of Thermonuclear Supernovae

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.Comment: 3 pages, 2 figures, aa.cls LaTeX, accepted by Astron.Asrophys.Letter

Energy exchange inside SN ejecta and light curves of SNe Ia

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.Comment: 4 pages 4 figures. 11th Workshop on "Nuclear Astrophysics", Ringberg Castle, Tegernsee, Germany, February 11-16, 2002. Small corrections to the published version in the text and figures 3,

Supernova Explosions inside Carbon-Oxygen Circumstellar Shells

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.Comment: Plain LaTeX, 11 pages, 24 ps files for 12 figures; refs added, small changes in the tex

Spectral Characteristics of Ultrashort Pulses in Kerr-lens Mode-Locked Lasers

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 lasersComment: 13 pages, 8 figures, 3 tables, LaTeX2e, spie.sty, psfig.st

Shock breakouts in SNe Ib/c

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.Comment: 4 pages 4 figures. 11th Workshop on "Nuclear Astrophysics", Ringberg Castle, Tegernsee, Germany, February 11-16, 2002. Minor correction

X-ray emission of young SN Ia remnants as a probe for an explosion model

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.Comment: 6 pages, 6 figures, poster presented at the 34th COSPAR Sci. Assembly, Houston, 10-19 october 200

Light Curves of Type Ia Supernovae as a Probe for an Explosion Model

We present theoretical UBVI- and bolometric light curves of SNe Ia for several explosion models, computed with our multi-group radiation hydro code. We employ our new corrected treatment for line opacity in the expanding medium. The results are compared with observed light curves. Our goal is to find the most viable thermonuclear SN model that gives good fits not only to a typical SN Ia light curves, but also to X-ray observations of young SN Ia remnants. It appears that classical 1D SN Ia models, such as deflagration model W7 and delayed detonation one DD4, fit the light curves not so good as a new 3D deflagration model by Reinecke et al. (which is averaged over angles for our LC modelling). This model seems good also in reproducing X-ray observations of Tycho SNR. We believe that the main feature of this model which allows us to get correct radiation during the first month, as well as after a few hundred years, when an SNR forms, is strong mixing that pushes material enriched in iron and nickel to the outermost layers of SN ejecta

Light Curve Models of Supernovae and X-ray spectra of Supernova Remnants

We compare parameters of well-observed type II SN1999em derived by M.Hamuy and D.Nadyozhin based on Litvinova-Nadyozhin (1985) analytic fits with those found from the simulations with our radiative hydro code Stella. The difference of SN parameters is quite large for the long distance scale. The same code applied to models of SN1993J allows us to estimate systematic errors of extracting foreground extinction toward SN1993J suggested by Clocchiatti et al. (1995). A new implicit two-temperature hydro code code Supremna is introduced which self-consistently takes into account the kinetics of ionization, electron thermal conduction, and radiative losses for predicting X-ray spectra of young supernova remnants such as Tycho and Kepler.Comment: 7 pages, 10 figures, Supernovae as Cosmological Lighthouses, Padua, June 16- 19, 2004, eds. M.Turatto et al., ASP Conference Serie

Time-dependent thermal effects in GRB afterglows

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.Comment: Revised vesrion. Minor changes, typos corected, reference added. To appear in Proc. 2d BeppoSAX Symposium, Eds. E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers. Nucl. Physics B.Suppl. Se