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Session 27 - Variable Stars, Novae, & Supernovae.
Display session, Tuesday, June 10
South Main Hall,
In recent years there has been wide recognition of the presence of multi-dimensional convective phenomena in the post-bounce epoch of core collapse supernovae. However, the numerical models of this phenomena have often contained either cursory treatments of neutrino transport or have made the assumption that the neutrino distribution can be characterized as a Fermi-Dirac distribution parametrized by a neutrino temperature and chemical potential. Recent work by Mezzacappa et al. (1996) and Swesty (1996) have shown that these assumptions can lead to substantial differences in the dynamics of the convection. Furthermore the work by Mezzacappa et al. has shown that the inclusion of multi-group neutrino transport may possibly hinder the development of an explosion. In order to more accurately describe the flow of neutrinos through the collapsing stellar core we have developed a 2-D multi-group flux-limited-diffusion radiation hydrodynamics code that fully couples the neutrinos to matter without making assumptions about the neutrino distributions. The algorithm employed in this code is a modification of the ZEUS-2D algorithm developed by Stone, Norman, amp; Mihalas (1992). We present the results of multi-group models we have conducted using this code. We will also contrast the results of multi-group models to the results of gray transport models, which assume a spectral distribution for the neutrinos. Comparisons of both the dynamics of the matter and the neutrinos will be made between the two classes of models. We will also discuss the approximations that have to be made to include the weak-interaction physics in each class of models. The models include a realistic parameterized equation of state (EOS). We will discuss parameter studies in which the nuclear force parameters have been varied in the EOS. Finally, we consider multiple progenitor masses in order to delineate the role of the progenitor model in the dynamics of the collapse.
