Collaborative Research: WoU-MMA: Revealing the Fate of Heavy Nuclei in Stellar Explosions and Pathways to Cosmic Rays

宇宙射线是从外太空到达地球的亚原子粒子。一些宇宙射线是人类迄今为止探测到的能量最高的粒子，远远超过了最大的粒子加速器实验产生的能量。这些超高能量宇宙射线的起源及其质量分布仍然是一个谜。弗吉尼亚理工学院、州立大学和宾夕法尼亚州立大学之间的一项科学合作将开展一项研究计划，旨在通过建立与大质量恒星以及两种不同但相关的爆炸恒星：超新星和伽马射线爆发的详细联系，进一步了解超高能宇宙射线（UHECR）的起源。这项研究将集中于了解超高能量宇宙射线的质量分布，这将用于解决解开宇宙射线起源的长期挑战。这项工作将受益于不断发现的超新星爆炸是如何驱动的，以及一种新的多信使天文学的发展，这种天文学将传统的光观测与宇宙射线和其他太空粒子的观测相结合。这项研究是跨学科的，需要详细的天体物理数值模型，核物理的应用，以及亚原子粒子加速和相互作用的考虑。最后，该项目还包括针对当地高中的积极推广计划。其核心是集成了一款名为Crayfis的智能手机应用程序，该应用程序通过智能手机ccd网络触发宇宙射线产生的被称为μ子的粒子来检测UHECR。该应用程序将被用作分享天体物理学和发现的兴奋的催化剂，它将利用现有的弗吉尼亚理工大学QuarkNet基础设施与高中教师合作，从而接触到更大范围的学生。将进行全面的数值研究，从喷流中原子核的起源到它们通往超高能量宇宙射线的途径。这些研究将提供超高能宇宙射线质量组成的预测，并允许与超高能宇宙射线和多信使观测进行定量比较。该提案的主要任务是：(i)建立发动机驱动的超新星和伽马射线爆发射流的核质量组成的详细预测；（ii）量化在射流传播、宇宙射线在耗散区的加速和宇宙射线在星系间空间的传播过程中对这种核丰度的修正；（iii）对宇宙射线和多信使观测数据进行信号预测；（iv）与数据进行定量比较。总之，这些任务将对发动机驱动的超新星和伽马射线爆发作为超高能量宇宙射线核的来源进行定量评估。这个项目推进了NSF宇宙大构想窗口的目标。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cosmic rays are sub-atomic particles that reach the earth from outer space. Some cosmic rays are the highest energy particles ever detected by humans, far exceeding the energies produced in the largest particle accelerator experiments. The origin of these ultra-high energy cosmic rays and the distribution of their masses remains a mystery. A science collaboration between Virginia Polytechnic Institute and State University and Pennsylvania State University will carry out a research program designed to further knowledge of the origins of ultra-high energy cosmic rays (UHECR) by establishing detailed connections to massive stars, and to two different, but related types of exploding stars: supernovae and gamma-ray bursts. The research will focus on understanding the distribution of masses of ultra-high energy cosmic rays, which will be used to address long-standing challenges in the quest for unraveling the origins of cosmic rays. The work will benefit from ongoing discoveries of how supernovae explosions are driven, and the development of a new multi-messenger astronomy that combines traditional observations of light with observations of cosmic rays and other particles from space. The research is interdisciplinary, requiring detailed astrophysical numerical models, applications of nuclear physics, and considerations of sub-atomic particle acceleration and interactions. Finally, the project includes an active outreach program aimed at local high schools. The centerpiece is the integration of a smartphone app "Crayfis" that detects UHECR by a network of smartphone CCDs triggering on the particles called muons created by the cosmic-rays. The app will be used as a catalyst to share excitement in astrophysics and discovery and it will leverage the existing Virginia Tech QuarkNet infrastructure to work with high school teachers, thereby reaching out to a large and broad range of students.A comprehensive numerical study, starting from the origins of nuclei in jets to their pathways to ultra-high energy cosmic rays, will be performed. These studies will deliver predictions for the mass compositions of ultra-high energy cosmic rays and allow quantitative comparisons with ultra-high energy cosmic-ray and multi-messenger observables. The main tasks of the proposal are: (i) to establish detailed predictions for the nuclear mass compositions of engine-driven supernovae and gamma-ray burst jets; (ii) to quantify the modification to such nuclear abundances during jet propagation, cosmic-ray acceleration in dissipation regions, and cosmic-ray propagation in intergalactic space; (iii) to make signal predictions for cosmic ray and multi-messenger observables; and (iv) to perform quantitative comparisons with data. Together, these tasks will deliver a quantitative assessment of engine-driven supernovae and gamma-ray bursts as sources of ultra-high energy cosmic ray nuclei. This project advances the goals of the NSF Windows on the Universe Big Idea.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.