Theoretical light curves for deflagration models of type la supernova

Abstract

Aims. We present synthetic bolometric and broad-band UBVRI light curves of SNe la for four selected 3D deflagration models of thermonuclear supernovae. Methods. The light curves are computed with the ID hydro code STELLA, which models (multi-group time-dependent) non-equilibrium radiative transfer inside SN ejecta. Angle-averaged results from 3D hydrodynamical explosion simulations with the composition determined in a nucleosynthetic postprocessing step served as the input to the radiative transfer model. Results. The predicted model UBV light curves do agree reasonably well with the observed ones for SNe la in the range of low to normal luminosities, although the underlying hydrodynamical explosion models produced only a modest amount of radioactive 56Ni (i.e. ∼0.24-0.42 M⊙) and relatively low kinetic energy in the explosion (less than 0.7 × 1051 erg). The evolution of predicted B and V fluxes in the model with a 56Ni mass of 0.42 M⊙ follows the observed decline rate after the maximum very well, although the behavior of fluxes in other filters deviates somewhat from observations, and the bolometric decline rate is a bit slow. The material velocity at the photospheric level is on the order of 104 km s-1 for all models. Using our models, we check the validity of Arnett's rule, relating the peak luminosity to the power of the deposited radioactive heating, and we also check the accuracy of the procedure for extracting the 56Ni mass from the observed light curves. Conclusions. We find that the comparison between theoretical light curves and observations provides a useful tool to validate SN 1a models. The steps necessary for improving the agreement between theory and observations are set out. © ESO 2006.