AST- 9713234 ABSTRACT - J. M. Dawson COLLECTIVE ABSORPTION PROCESSES OF NEUTRINOS IN SUPERNOVAE A program to investigate the influence of collective interactions of the intense neutrino flux from the core of a supernova with the plasma of it's surrounding stellar envelope will be carried out. The mechanism is similar to the Forward Raman Instability that occurs when intense light interacts with plasma by generating electron plasma waves. In the neutrino case, the instability is much weaker due to the weakness of the neutrino electron interaction. Recent work at UCLA has shown that because of the extreme conditions that exist in a supernova, the forward Raman instability takes place. In the photon plasma case this instability increases the interaction with the plasma by many orders of magnitude. By analogy, large enhancements of the neutrino plasma coupling can be expected. The neutrinos carry away most of the energy of the supernova (100 times the light output). Models of supernova explosions have run into problems explaining how the supernova explodes if so much energy is carried off by the neutrinos and additional energy must be expended in dissociating iron and other heavy nuclei. Explosions can be made to occur if a few percent of the neutrino energy can be deposited in the stellar envelope. The forward Raman instability appear to be strong enough to do this and thus to influence the dynamics of the supernova. Techniques for computing the transport of the neutrinos through the stellar plasma and the resulting energy transfer will be developed. This will involve two quasi-linear equations, one for neutrinos and one for electrons, plus an equation for the evolution of plasma waves. The quasi-linear equation for the neutrinos describe the evolution of the neutrino spectrum due to their interaction with the plasma waves. The plasma wave equation computes the spectrum of plasma waves produced by the neutrinos and includes damping by electrons and the r esultant flow of energy from neutrinos to electrons. The quasi linear equation for the electrons describes the evolution of the electron distribution function; this is primarily a heating. When the electrons become hot enough (~ 500Kev) the Forward Raman Instability becomes the Forward Stimulated Compton Instability because the waves become heavily Landau damped. It is expected that the Forward Stimulated Compton Instability will be much weaker and to effectively turn off. Computer software codes to solve these coupled equations will be written and then used to explore the neutrino energy deposited in the electrons and the electron temperatures reached as a function of position in the star. The effects of the interaction on the neutrino energy distribution will be calculated to explore possible signatures of the process that might be detectable.
