Multilevel Structure of Cellular Detonations in Type Ia Supernovae

Abstract

This work presents the results of a numerical study of two-dimensional cellular thermonuclear detonations in degenerate C+O matter at densities 106-3×107 g cm-3. We found three levels of detonation cells of very different sizes which correspond to the C-, O-, and Si-reaction length scales. The Si cells are comparable to or even larger than the white dwarf size at densities below 107 g cm-3. In the presence of the cellular structures, the averaged half-reaction length compared to the one-dimensional case increases by the factor of 1.3 for the Si-reaction, and by a factor of 1.6 for the O- and C-reactions. The formation of unreacted pockets and overreacted regions behind the cellular detonation front creates concentration fluctuations in the reaction zone. The composition fluctuations and the reaction length increase may affect the spectra of Type Ia supernovae predicted by delayed-detonation models.