Collaborative Research: WoU-MMA: Multi-scale and multi-messenger modeling of jets in active galactic nuclei

星系是数千亿颗恒星的巨大集合。在少数星系中，观测到的光主要来自一个单一的光源：位于星系中心的超大质量黑洞。在这些星系中，黑洞以物质为食，这些物质会变成非常热的电离气体或等离子体。令人惊讶的是，这些物质的一部分被从黑洞中喷射出来，形成了以接近光速运动的窄束等离子体。当这些光束指向地球时，就会成为宇宙中观测到的最亮、最极端的光源之一。提出建议的团队计划进行最大规模的数值模拟，以研究物质如何从星系的巨大尺度落入黑洞的微小尺度，并跟踪等离子体的窄速光束在星系中传播时如何形成和发光。数值模拟的结果将通过一个用户友好的交互式网站向公众开放。用户（科学家、教师或高中生）将能够实时生成这些光束的图像，因此将暴露在一个令人兴奋的现代高能天体物理学领域。冰立方中微子天文台最近探测到一个高能中微子事件，该事件与blazar TXS 0506+056的多波长耀斑相一致，这强烈表明blazar不仅产生高能光子，还产生超高能宇宙射线和中微子。这一令人兴奋的多信使发现激发了对相对论喷流物理学的详细研究，以解释这一发现以及即将到来的对活动星系核（AGN）的多信使观测。该团队建议进行多尺度射流模拟，将吸积物理、流体动力学、粒子加速和辐射传递联系起来，研究AGN射流的多波长极化辐射特征和中微子。该团队计划对AGN吸积和喷流进行迄今为止最大规模的广义相对论磁流体动力学模拟，从黑洞延伸到耀焰发射区。他们将使用第一性原理动力学等离子体模拟来计算射流耗散区的粒子加速度，并建立包括所有相关物理在内的综合多信使极化辐射传输。通过这种方式，该团队可以弥合第一原理建模和多信使观测之间的差距，并推进对AGN多信使发射的喷气物理的理解。该团队将通过一个沉浸式网站向公众传播结果，培训高中生，并为研究生组织一个紧凑对象的暑期学校，参与者将在研究领域的前沿研究理论和/或数值问题。该奖项旨在解决/推进宇宙之窗大构想的目标。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。

Part 1Galaxies are vast collections of hundreds of billions of stars. In a minority of the galaxies their observed light is dominated by a single source: the supermassive black hole located at their very center. In these galaxies, the black hole feeds on material which turns into very hot ionized gas or plasma. Surprisingly, part of this material is ejected away from the black hole forming narrow beams of plasma that move at near the speed of light. These beams, when directed at Earth, make some of the brightest and extreme sources ever observed in the Universe. The proposing team plans to perform the largest numerical simulations to study how matter falls from the vast scale of the galaxy into the tiny scale of the black hole and follow how the narrow fast beams of plasma form and shine as they propagate through the galaxy. The results from the numerical simulations will be publicly accessible through a user-friendly, interactive website. The user (scientist, teacher or high-school student) will be able to generate images of these beams in real-time and will thus be exposed to an exciting field of modern high-energy astrophysics.Part 2Recent detection by the IceCube Neutrino Observatory of a very high energy neutrino event coincident with multi-wavelength flaring of blazar TXS 0506+056 strongly suggests that blazars do not only produce high-energy photons but also ultra-high-energy cosmic rays and neutrinos. This exciting multi-messenger discovery motivates a detailed study of relativistic jet physics, to interpret this and upcoming multi-messenger observations of active galactic nuclei (AGN). The team proposes to perform multi-scale jet simulations that connect accretion physics, fluid dynamics, particle acceleration, and radiative transfer, to study the multi-wavelength polarized radiation signatures and neutrinos from AGN jets. The team plans to perform the largest to date general relativistic magnetohydrodynamic simulations of AGN accretion and jets, extending from the black hole to the blazar emission zone. They will use first-principle kinetic plasma simulations to calculate particle acceleration in jet dissipation zones and build comprehensive multi-messenger polarized radiative transfer that includes all the relevant physics. In this way, the team can bridge the gap between first-principle modeling and multi-messenger observations, and advance the understanding of AGN jet physics responsible for multi-messenger emission. The team will disseminate the results to the public through an immersive website, train high-school students, and organize a summer school in compact objects for graduate students, where participants will work on theoretical and/or numerical problems at the forefront of the research field.This award addresses/advances the goals of the 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.