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Session 39 - Supernovae.
Display session, Thursday, January 08
Exhibit Hall,

[39.09] Grey and Multigroup Models of Core Collapse Supernovae

F. D. Swesty (Dept. of Astronomy and NCSA, U. Illinois)

Recently, there has been a growing recognition of the role of neutrino reheating in convective explosion models for core collapse supernovae. The results of the multigroup models of Mezzacappa et al. (1997) have indicated that improved neutrino transport models may increase the difficulty of obtaining explosions in computational radiation hydrodynamic models of supernovae. To date most multi-dimensional models of core collapse supernovae have relied upon the use of some form of flux-limited diffusion gray approximation to neutrino transport. In this approximation the spectral characteristics of the neutrino flux in the optically thin regions of the collapsed core are assumed and the energy flow of the neutrinos is described by a single radiation energy equation. A better model of neutrino transport is obtained by employing multigroup flux limited diffusion which explicitly models the evolution of the spectrum throughout the core by employing a series of monochromatic radiation energy equations to describe the evolution of the neutrinos. We will present results from both multigroup and gray models of the convective epoch of post-core-bounce supernovae. We will focus on the differences and problems of each of these approximations. We will discuss the heating rates, the strength of the convection, and the the effects of various neutrino-matter interaction rate implementations. The models include a realistic parameterized equation of state (EOS) and three flavors of neutrinos. We will discuss issues of numerical resolution and present the results of numerical convergence studies. Finally, we consider how the features of the models vary with progenitor mass.

Program listing for Thursday