New Challenges to Astrophysical Particle Acceleration

尽管宇宙射线在近一个世纪前就被发现了，但它们在哪里、如何加速以及如何传播给我们的细节仍然有些神秘。加速可以发生在许多宇宙源中，包括旋转、磁化的中子星、大质量黑洞、伽马射线爆发、超新星爆炸产生的冲击波，甚至是星系团周围类似但更大的冲击波。由于最近的发现，以及对宇宙射线的光谱和组成的大大改进的测量，这个领域正在恢复活力。这个项目是对宇宙粒子加速机制的理论研究，涵盖了几个地点，并对最近的观测做出了回应。它将探索被称为单极感应的机制，并详细分析粒子如何在非常小的步骤中获得能量和动量，例如在激波锋面附近。定性的新型磁重联和相对论性激波前沿将使用简单的分析和更详细的模拟进行研究。这些结果应该有助于解释最近对宇宙源的惊人观测，包括70倍频的电磁波谱及其他波段。尽管人们关注了一个世纪，但这些问题只得到了部分理解，通过观察和模拟来解决这些问题将需要相当复杂的工具。这项工作与太阳天气、磁场和惯性聚变的研究有着广泛的联系，这些都是公众感兴趣和社会关注的话题。学生将在等离子体天体物理学方面获得宝贵的训练，这是为许多其他领域做准备的良好准备。

Although cosmic rays were discovered almost a century ago the details of where and how they are accelerated and how they propagate to us remain somewhat mysterious. Acceleration can occur in many cosmic sources, including spinning, magnetized neutron stars, massive black holes, gamma ray bursts, shock waves expanding from supernova explosions, and even similar but larger shocks surrounding clusters of galaxies. The field is being revitalized by recent discoveries, and by greatly improved measurements of the spectra and composition of cosmic rays. This project is a theoretical investigation of cosmic particle acceleration mechanisms spanning several sites and responding to recent observations. It will explore the mechanism known as unipolar induction, and analyze in detail how particles can acquire energy and momentum in very small steps, such as in the vicinity of shock fronts. Qualitatively new types of magnetic reconnection and relativistic shock fronts will be studied using both simple analysis and more detailed simulations. The results should help to explain recent surprising observations of cosmic sources, throughout the seventy octave electromagnetic spectrum and beyond.These problems have been only partially understood despite a century of attention, and tackling them both observationally and through simulation will require quite sophisticated tools. The work links broadly to the study of solar weather, and of magnetic and inertial fusion, topics of strong public interest and societal concern. A student will receive valuable training in plasma astrophysics, which is a good preparation for many other fields.