EAGER: Novel Approach to Acceleration and Escape of Charged Particles at Interplanetary and Astrophysical Shock Waves

冲击波中粒子加速的模型有望为更好地理解宇宙射线的起源铺平道路，宇宙射线是100多年前发现的。现有的扩散激波加速(DSA)标准模型适用于理想无限平面激波阵面的情况；如果粒子能够对比流动平流并返回激波进行进一步的加速，则加速过程是自持续的。如果粒子不能被限制在激波附近，那么DSA方法是不可行的。这个为期一年的项目的主要重点是探索一种新的方法来解释观察到的不符合DSA范例的高能粒子。这一方法将包括分析和数值分析，以支持对航天器数据的解释。该研究项目将产生一个先进的理论模型，可以解释对地球附近激波的测量，以及对各种天体物理源的观测，包括脉冲星风星云、blazar、超新星遗迹等。这个为期一年的急切项目旨在改变我们目前对带电粒子在行星际和天体物理冲击波中加速的理解。几个行星际激波事件显示出高能粒子的破缺幂函数谱。这样的光谱不在标准扩散激波加速(DSA)模型的有效性范围之内，尽管在几个案例中观察到了这些光谱，但到目前为止对它的研究还很少。这个项目建立在之前的一项努力的基础上，解释了观测到的来自天体物理来源的电磁辐射--高能电子的对数抛物线谱，而不是经验的多重幂定律--令人惊讶地很好地解释了蟹状星云在前所未有的广泛能量范围内的观测。该项目团队的总部设在亚利桑那大学，旨在确定导致对数抛物线频谱的物理条件，这将导致该领域的范式转变。该团队将使用在项目期间收集的新知识来教育普通公众关于空间天气的物理驱动因素及其影响。这个热切的项目的研究和EPO议程支持AGS部门在发现、学习、多样性和跨学科研究方面的战略目标。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The modelling of particle acceleration at shocks is expected to pave the path to improved understanding of the origin of cosmic-rays, which were discovered more than 100 years ago. The current standard model of Diffusive Shock Acceleration (DSA) applies to the case of ideal, infinitely planar shock front; the process of acceleration is self-sustained if particles can contrast the flow advection and return to the shock to undergo further acceleration. If particles cannot be confined in proximity of the shocks, then the DSA approach is not feasible. The main focus of this one-year EAGER project is to explore a novel approach to explain the observations of energetic particles that do not fit in the DSA paradigm. This approach will comprise both analytic and numerical analyses, which support the interpretation of spacecraft data. The research project will produce an advanced theoretical model that may explain the measurements of shocks near the Earth, as well as observations of a variety of astrophysical sources, including pulsar wind nebulae, blazars, supernova remnants, etc.This one-year EAGER project is aimed at transforming our present understanding of the acceleration of charged particles at interplanetary and astrophysical shock waves. Several interplanetary shock events exhibit broken power-law spectra of the energetic particles. Such spectra fall outside the regime of validity of the standard Diffusive Shock Acceleration (DSA) model and, despite observed in several cases, have been poorly studied to date. This project builds upon a previous effort to interpret the observed electromagnetic radiation from astrophysical sources -- a log-parabola spectrum of energetic electrons, instead of empirical, multiple power-laws -- that explains surprisingly well the observations of the Crab Nebula over an unprecedentedly broad energy range. The project team, which based at the University of Arizona, aims to determine the physical conditions that give rise to a log-parabola spectrum, which would yield a paradigm shift in the field. The team will use the new knowledge gathered during the project to educate the general public about the physical drivers of space weather and their impacts. The research and EPO agenda of this EAGER project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.