Bridging grant application for VERITAS: Investigating the origin of high-energy particles in the Universe with multi-messenger observations

地球不断受到来自太阳系外的被称为宇宙射线的高能带电粒子的轰击。虽然这些宇宙射线在1912年首次被发现，但它们的起源以及它们如何传播到地球仍然不清楚。尽管在过去十年中宇宙射线科学取得了一些重要进展，但很明显，多信使方法对于揭示宇宙射线产生和传播的全貌至关重要。在这种方法下，中性粒子，如伽马射线和中微子，它们是由宇宙射线与我们宇宙中的环境相互作用产生的，与庞大的宇宙射线数据集结合使用，以查明这些带电粒子的最终起源。该提案要求为申请人提供一年的支持，以与2022年秋季现有的VERITAS（高能辐射成像望远镜阵列系统）合作项目资金同步。VERITAS是一个位于美国图森附近的地面探测器，致力于研究能量高于100 GeV的天体物理伽马射线。VERITAS是为研究甚高能（VHE）伽马射线而建造的三个大型望远镜阵列之一，通过发现新的来源和测试VHE范围内的基础物理学，为我们对宇宙中高能粒子的了解做出了贡献。该应用程序旨在利用VERITAS的完整数据集来研究银河系的伽马射线漫发射，通过后续观测来寻找高能宇宙射线和中微子的起源，并改进VERITAS的数据分析。这项拟议中的研究将为解决一个100年前的问题做出重大贡献：宇宙射线的起源是什么？它们是如何到达地球的？我将开发一种新的方法，从VERITAS在过去十年中积累的8,000多小时的数据中生成纯伽马射线数据集。结果将揭示第一次测量弥漫伽马射线发射在北方半球的VERITAS类探测器。寻找银河系晕内的弥散伽马射线发射将提供对晕内宇宙射线和暗物质相互作用的深入了解。高能中微子的后续观测将为探测高能宇宙射线和中微子的起源提供急需的多信使观测样本。该研究还将在我的团队中培养四名HQP：1名硕士生，2名本科生和1名博士后，他们具有在学术和工业环境中都有价值的独特技能，包括处理大型数据集，熟悉各种计算机编程语言和技术，以及使用复杂的机器学习技术分析数据。它还将为HQP提供操作VERITAS望远镜的机会，并获得处理和维护探测器系统的经验。

The Earth is continuously bombarded by high-energy charged particles known as cosmic rays, which arrive from outside of the solar system. Although these cosmic rays were first discovered in 1912, their origins and how they propagate to Earth remain unclear. Notwithstanding several important advances in cosmic-ray science in the last decade, it has become evident that a multi-messenger approach is essential to reveal a complete picture of cosmic-ray production and propagation. Under such an approach, neutral particles such as gamma rays and neutrinos, which are created by the interactions of cosmic rays with the environment within our Universe, are used in conjunction with the vast cosmic-ray data set to pinpoint the ultimate origins of these charged particles. This proposal requests one year of support for the applicant to synchronize with the existing VERITAS (Very Energetic Radiation Imaging Telescope Array System) collaboration project funding in fall 2022. VERITAS is a ground-based detector located near Tucson, US, pursuing studies of astrophysical gamma rays with energies higher than 100 GeV. One of three large telescope arrays built for the study of very-high-energy (VHE) gamma rays, VERITAS has contributed to advancements in our knowledge of high-energy particles in our Universe by discovering new sources and by testing fundamental physics in the VHE range. This application aims to exploit the full data set of VERITAS to study the gamma-ray diffuse emission from our Galaxy, to hunt down the origin of high-energy cosmic rays and neutrinos with followup observations, and to improve the data analysis of VERITAS. The proposed research will make substantial contributions to the resolution of a 100-year-old question: what are the origins of the cosmic rays and how do they travel to Earth? I will develop a novel method to generate a gamma-ray-pure data set from over 8,000 hours of data that VERITAS has accumulated over the past ten years. The result will reveal the first measurements of diffuse gamma-ray emission in the northern hemisphere by a VERITAS-like detector. The search for diffuse gamma-ray emission inside the Galactic halo will provide insight into the interactions of cosmic rays and dark matter within the halo. The high-energy neutrino followup observations will provide much-needed samples of multi-messenger observations to probe the origin of high-energy cosmic rays and neutrinos. The research will also train four HQPs in my group: 1 Master's degree student, 2 undergraduate students, and 1 postdoctoral fellow, with unique skills that are valuable in both academic and industrial settings, including the handling of large data sets, familiarity with a wide range of computer programming languages and technologies, and the analysis of data using sophisticated machine learning techniques. It will also provide opportunities for HQPs to operate the VERITAS telescopes and gain experience in handling and maintaining the detector system.