Particle-in-cell simulation of the neutrino fast flavor instability
Particle-in-cell simulation of the neutrino fast flavor instability
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DOI：
10.1103/physrevd.103.083013
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发表时间：
2021-01
影响因子：
5
通讯作者：
S. Richers;D. Willcox;N. Ford;A. Myers
中科院分区：
文献类型：
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作者：
S. Richers;D. Willcox;N. Ford;A. Myers
中微子驱动核心坍缩的超新星，从中子星合并吸积盘中发射出物质，并在两个产生宇宙重元素的系统的喷射物中设定质子与中子的比例。不同口味的中微子与物质的相互作用不同，最近的许多研究表明，在这两种体系中，快速风味不稳定性可能普遍存在，但不稳定性饱和后的最终风味含量尚未得到很好的理解。在这项工作中，我们提出了粒子在细胞中的计算，通过饱和和运动退相干来跟踪所有类型的中微子和反中微子的演化。我们对中微子量子动力学进行了一维三味模拟，以证明这种不稳定性在几个例子中的结果。我们证明了轴对称和非对称模式的生长，其波长和生长速率与线性稳定性分析的预测相匹配。最后，我们改变了中微子和反中微子的数量密度、通量大小和通量方向，并证明了这些因素会改变中微子的生长速度和饱和后的中微子风味丰度。在这些模拟中，弱电子轻子数（ELN）交叉导致不稳定性增长缓慢，且初始态和终态的风味丰度差异不大。在所有这些计算中，相同数量的中微子和反中微子会改变味道，使它们之间最不丰富的中微子成为饱和后味道变化的限制因素。为了充分探测初始条件的参数空间，需要进行更多的仿真和多维仿真。
Neutrinos drive core-collapse supernovae, launch outflows from neutron star merger accretion disks, and set the ratio of protons to neutrons in ejecta from both systems that generate heavy elements in the universe. Neutrinos of different flavors interact with matter differently, and much recent work has suggested that fast flavor instabilities are likely ubiquitous in both systems, but the final flavor content after the instability saturates has not been well understood. In this work we present particle-in-cell calculations which follow the evolution of all flavors of neutrinos and antineutrinos through saturation and kinematic decoherence. We conduct one-dimensional three-flavor simulations of neutrino quantum kinetics to demonstrate the outcome of this instability in a few example cases. We demonstrate the growth of both axially symmetric and asymmetric modes whose wavelength and growth rate match predictions from linear stability analysis. Finally, we vary the number density, flux magnitude, and flux direction of the neutrinos and antineutrinos and demonstrate that these factors modify both the growth rate and post-saturation neutrino flavor abundances. Weak electron lepton number (ELN) crossings in these simulations produce both slow growth of the instability and little difference between the flavor abundances in the initial and final states. In all of these calculations the same number of neutrinos and antineutrinos change flavor, making the least abundant between them the limiting factor for post-saturation flavor change. Many more simulations and multi-dimensional simulations are needed to fully probe the parameter space of the initial conditions.