Very High Energy Astrophysics with VERITAS

伽马射线天文学探索系统的极端物理学，如活跃星系中心的黑洞或超新星爆炸的残余物，这些爆炸结束了许多巨星的生命。这些系统发射的辐射遍及整个电磁频谱，现在地面探测器可观测到的极高能伽马射线能量带中有数百个可探测到。VERITAS伽马射线天文台位于F。L.亚利桑那州的维普莱天文台一直是并将继续是该领域扩展的关键驱动力，其发现与从多波长望远镜获得的信息相结合，大大增加了我们对宇宙中最具活力的过程的理解。 明尼苏达大学的VERITAS团队，包括博士后和学生研究人员，专注于可以帮助破译活跃星系如何为伽马射线的发射提供动力的调查，以及与超高能宇宙射线和天体物理中微子产生起源的可能联系，这是该领域的两个突出问题。该团队还在为原型Schwarzschild-Couder望远镜开发校准技术，该望远镜被设想为下一代切伦科夫望远镜阵列的组成部分。通过这一努力，一个通过Zooniverse.org的公民科学项目通过众包的VERITAS图像分类为公众参与伽马射线相关科学提供了直接机会，这将改善天体物理物体的分类。地基甚高能（VHE）伽马射线天体物理学在过去十年中已经成熟为一个领域，将VHE目录从少数扩展到200多个对象，涵盖了代表宇宙中最极端现象的各种源类。VERITAS的观测结合了从无线电到X射线的大量多波长数据，特别是来自美国宇航局费米-LAT卫星的高能伽马射线，大大增加了我们对宇宙中最具活力的过程的理解。在这笔赠款下开展的工作对于保持VERITAS的敏感性至关重要，以最大限度地提高整个频谱以及多信使观测站数据采集活动的科学回报。新的分析方法的目标是提高对弱源的灵敏度，实施监测和解释整体探测器吞吐量变化的修改，并解决观测站记录的最高能量下的系统不确定性。这些努力将使新的VHE发射活动星系核（AGN）的发现和已知的VHE耀变体的观测，其目标是更好地表征所谓的耀变体序列，该序列假定耀变体亮度和峰值同步辐射发射频率之间的反比关系可能是由于宇宙演化。它还将使调查耀变体光谱在高光学深度，吸收功能，由于伽玛射线相互作用的河外光子场变得重要。这项工作的结果也可用于阐明耀变体中伽马射线发射背后的天体物理学及其与超高能宇宙射线起源和天体物理中微子产生的联系。该奖项反映了NSF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。

Gamma-ray astronomy probes the extreme physics of systems such as the black holes at the centers of active galaxies or the remnants of supernova explosions that end the lives of many giant stars. These systems emit radiation throughout the electromagnetic spectrum and hundreds are now detectable in the very-high-energy gamma-ray energy band observable by ground-based detectors. The VERITAS gamma-ray observatory, located at the F. L. Whipple Observatory in Arizona, has been and continues to be a key driver of the field’s expansion, making discoveries that, combined with the information obtained from telescopes operating at multiple wavelengths, has significantly increased our understanding of the most energetic processes in the Universe. The VERITAS team at the University of Minnesota, involving postdoctoral and student researchers, focuses on investigations that can help decipher how active galaxies power the emission of gamma rays and the possible links to the origin of ultra-high-energy cosmic rays and astrophysical neutrino production, two outstanding questions in the field. The team is also developing calibration techniques for the prototype Schwarzschild-Couder Telescope envisaged as a component of the next-generation Cherenkov Telescope Array. Through this effort, a citizen science project via Zooniverse.org provides direct opportunities for public participation in gamma-ray related science via crowdsourced classifications of VERITAS images that will improve the classification of astrophysical objects. Ground-based very-high-energy (VHE) gamma-ray astrophysics has matured as a field in the last decade, expanding the VHE catalog from a handful to over 200 objects across a wide range of source classes that represent the most extreme phenomena in the Universe. VERITAS observations combined with a wealth of multi-wavelength data from radio to X-ray, and especially high-energy gamma rays from NASA’s Fermi-LAT satellite, has significantly increased our understanding of the most energetic processes in the Universe. The work carried out under this grant is crucial to maintaining the sensitivity of VERITAS to maximize the science return on data taking campaigns across the spectrum as well as with multi-messenger observatories. New analysis methods are targeted that boost sensitivity to weak sources, implement modifications that monitor and account for changes in the overall detector throughput, and address systematic uncertainties at the highest recorded energies by the observatory. These efforts will enable discoveries of new VHE emitting active galactic nuclei (AGN) and observations of known VHE blazars with the goal to better characterize the so-called blazar sequence that postulates an inverse relationship between blazar luminosity and peak synchrotron emission frequency potentially due to cosmic evolution. It will also enable the investigation of blazar spectra at high optical depth where absorption features due to gamma-ray interactions on the extragalactic photon fields becomes important. Results from this work can also be used to elucidate the astrophysics behind gamma-ray emission in blazars and its links to the origin of ultra-high-energy cosmic rays and astrophysical neutrino production.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.