Collaborative Research: Predicting the Transient Signals from Galactic Centers: Circumbinary Disks and Tidal Disruptions around Black Holes

超大质量黑洞的质量是太阳的数百万到数十亿倍，其强大的引力影响可以加热附近的气体，使其比整个恒星星系更耀眼，并以相对论的速度向外弹射物质。它们几乎存在于每一个大质量星系的中心，它们可能在调节恒星形成速度方面起着重要作用。我们的项目旨在对迄今为止最具戏剧性的两个事件进行最真实的模拟：两个绕轨道运行的超大质量黑洞的灵感和合并以及恒星的潮汐分裂。它们都曾被认为是不可观测的，但对瞬变现象非常敏感的大型天文调查的出现导致了许多潮汐破坏的发现，并有望发现许多合并。广泛观测数据的前景使两者都成为热门话题。这个项目的巨大优势在于它提供了一个机会，将许多现有的研究项目整合到一个由科学家、学生和公众组成的更大的社区中。它将促进塔尔萨大学、约翰霍普金斯大学、NASA/GSFC和罗切斯特理工学院的本科生、研究生、博士后研究人员和教师之间的跨学科合作。通过这样一个网络，我们以前非常成功的外展项目将能够接触到更大、更多样化的受众。例如，S. Noble （PI）将继续与参加每月一次的100-200名高中生讨论热门物理话题。杂志俱乐部吗?活动由他的部门赞助，并将与他的合作者在他们的机构建立类似的活动。该项目的主要目标是对环双星吸积和潮汐破坏事件的电磁特征做出具体的预测，这将使天文学家能够仅基于EM观测，利用HST（光学）、JWST（红外）、钱德拉（x射线）和ISS-Lobster （x射线），以及已经在运行的全景巡天望远镜和快速反应系统等地面仪器，识别这些壮观的事件。或者计划中的大型综合巡天望远镜。这样的识别将极大地帮助我们改进对合并的超大质量黑洞数量的估计，既可以估计潜在引力波目标的数量，也可以评估黑洞合并对星系演化的影响。我们在Blue Waters上的模拟将采用许多新的计算发展，以实现迄今为止这些系统最真实的模拟。它们包括一个自适应负载平衡器，以均匀地分配非均匀成本的运行，以及一个多补丁系统，用于在不同坐标域上演化磁流体动力学方程。我们的目的是使后一种工具在其他磁流体力学代码中公开可用。我们的科学成果也将在理论上和观测上对天体物理界产生广泛的影响。我们将发布详细的光谱和模拟数据，供观察员和未来的任务开发团队使用。随着时域和多信使天文学领域的迅速发展，这项工作来得正是时候。

With masses millions to billions times that of our Sun, the strong gravitational influence of supermassive black holes can heat nearby gas so that it outshines an entire galaxy of stars, and slingshot material outward at relativistic speeds. They exist at the centers of almost every massive galaxy, and they may play a significant role in regulating rates of star formation. Our project aims to produce the most realistic simulations to-date of two of the most dramatic events they can make: the inspiral and merger of two orbiting supermassive black holes and the tidal disruption of stars. Both were once thought to be unobservable, but the advent of very large astronomical surveys sensitive to transients have led to the discovery of numerous tidal disruptions and promise the discovery of many mergers. The prospect of extensive observational data make both very hot topics. The great advantage of this program is the opportunity it provides to integrate many existing research programs into a larger community of scientists, students, and the general public. It will foster crossdisciplinary collaborations among undergraduate students, graduate students, postdoctoral researchers and faculty at the Univ. of Tulsa, Johns Hopkins Univ., NASA/GSFC, and Rochester Institute of Technology. Through such a network, our previous highly successful outreach programs will be able to reach an even larger and more diverse audience. For instance, S. Noble (PI) will continue to speak about hot physics topics with the 100-200 high school students that attend the monthly ?Journal Club? event sponsored by his department, and will work with his collaborators on building similar activities at their institutions.The major goal of this project is to make specific predictions of electromagnetic signatures of circumbinary accretion and tidal disruption events that will allow astronomers to identify, based solely on EM observations, these spectacular events using HST (optical), JWST (IR), Chandra (X-ray), and ISS-Lobster (X-ray), as well as ground based instrumentation such as the Panoramic Survey Telescope and Rapid Response System, which is already in operation, or the planned Large Synoptic Survey Telescope. Such identifications will be a tremendous aid in refining our estimates of the population of merging supermassive black holes, both for estimating the numbers of potential gravitational wave targets and for evaluating the impact of black hole mergers on galaxy evolution. Our simulations on Blue Waters will employ a number of new computational developments needed to achieve the most realistic simulations of these systems to date. They include an adaptive load balancer to evenly distribute runs with nonuniform costs, and a multi-patch system for evolving the magnetohydrodynamics equations on different coordinate domains. It is our intent to make the latter tool publicly available for use in other magnetohydrodynamics codes. Our scientific results will also have a wide-reaching impact on the astrophysical community, both theoretically and observationally. We will release detailed spectra and simulation data for use by observers and future mission development teams. This work comes at a particularly opportune time, as the fields of time-domain and multi-messenger astronomy are growing rapidly.