Collective Absorption Processes of Neutrinos in Supernovae

超新星中中微子的集体吸收过程

• 批准号: 9713234
• 负责人: John Dawson
• 金额: $ 23.49万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-10-01 至 2000-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9713234&HistoricalAwards=false
• 关键词: Collective; Absorption; Processes; Neutrinos; Supernovae

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.

AST- 9713234摘要- J. M.道森 超新星中中微子的集体吸收过程 将进行一项计划，研究来自超新星核心的强中微子通量与周围恒星包层等离子体的集体相互作用的影响。该机制类似于前向拉曼不稳定性，当强光与等离子体相互作用时，通过产生电子等离子体波发生。 在中微子的情况下，由于中微子电子相互作用的弱点，不稳定性要弱得多。 加州大学洛杉矶分校最近的研究表明，由于超新星存在的极端条件，前向拉曼不稳定性发生。 在光子等离子体的情况下，这种不稳定性增加了与等离子体的相互作用许多数量级。 以此类推，可以预期中微子等离子体耦合的大幅增强。 中微子带走了超新星的大部分能量（光输出的100倍）。 超新星爆炸的模型在解释超新星爆炸时遇到了问题，如果中微子带走了这么多能量，那么额外的能量必须花费在解离铁和其他重核上。 如果有百分之几的中微子能量可以储存在恒星的包层中，爆炸就可以发生。 前向拉曼不稳定性似乎足够强，足以做到这一点，从而影响超新星的动力学。 将开发计算中微子通过恒星等离子体的传输和由此产生的能量转移的技术。 这将涉及两个准线性方程，一个是中微子，一个是电子，再加上一个等离子体波的演化方程。 中微子的准线性方程描述了由于中微子与等离子体波相互作用而导致的中微子谱的演化。 等离子体波方程计算由中微子产生的等离子体波的频谱，并包括电子的阻尼和从中微子到电子的能量的剩余流。 电子的准线性方程描述了电子分布函数的演化;这主要是一种加热。 当电子变得足够热（~ 500 Kev）时，前向拉曼不稳定性变成前向受激康普顿不稳定性，因为波变得严重朗道阻尼。 预计前向受激康普顿不稳定性将弱得多，并有效地关闭。 计算机软件代码来解决这些耦合方程将被写入，然后用来探索中微子能量沉积在电子和电子温度达到作为一个功能的位置在星星。 相互作用对中微子能量分布的影响将被计算出来，以探索可能被探测到的过程的可能特征。