GPU-enabled General Relativistic Simulations of Jetted Tidal Disruptions of Stars by Supermassive Black Holes

支持 GPU 的广义相对论模拟超大质量黑洞对恒星的喷射潮汐扰动

• 批准号: 1615281
• 负责人: Alexander Chekhovskoy
• 金额: $ 0.55万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1615281&HistoricalAwards=false
• 关键词: GPU; enabled; General; Relativistic; Simulations

Tidal disruption events (TDEs), which occur when a star is destroyed by the gravitationalfield of a supermassive black hole, are unique probes into the properties of otherwise-quiescentsupermassive black holes (SMBHs). About 30 of them have been observed so far and this numberis steadily increasing, aided with surveys and new instruments coming online. Despite thiswealth of observational knowledge, our understanding of the TDE physics, which will ultimatelyallow us to interpret those observations, remains rudimentary at best. In particular, we stilldo not understand what causes the debris to lose its energy and angular momentum, fall intothe black hole and radiate. This project will make use of the fact that, at their core,TDEs are ultimately well-described by the general relativistic magnetohydrodynamics (GRMHD)equations of motion. By carrying out direct GRMHD simulations of TDEs, the project hopes to obtain a first-principlesunderstanding of TDE physics. The proposed simulations will provide answers to several long-standingquestions in the TDE community: How does the debris circularize, dissipate energy, and accreteonto the SMBH? What fraction of stellar gas forms the disk, what fraction is ejected as anoutflow, and how do these fractions depend on the black hole mass, spin, and the inclinationof the stellar orbit? Do eccentric accretion disks form and how does angular momentum transportwork in such disks? If such an eccentric disk is tilted, as is naturally expected in TDEs,does it undergo general relativistic precession? Do such disks produce relativistic jets andhow? Understanding these issues will allow the community to make meaningful, quantitativeinterpretation of TDE observations.Even though the project is focused on TDEs, it elucidates the basicphysics of tilted accretion disks and their jets that is applicable to a range of sourcesincluding quasars, black hole binaries, and ultra-luminous X-ray sources. Additionally, the proposed simulations will study, from first principlesand for the first time, the development of magnetorotational instability in eccentric tiltedaccretion disks and the long-term evolution and GR precession of such disks under continuousfeeding by the debris stream.Moreover, stars shredded by black holes and producing relativistic jets offer someof the most fascinating manifestations of general relativity. The project will disseminate theresults obtained as part of this proposal in public talks, summer schools, radio station andnewspaper interviews, and press releases. Finally, the project will involve undergraduate students in dataanalysis and visualization, and they will gain experience in working with Big Data, blackhole accretion and jet physics, presenting their results at conferences, and publishing theirwork in peer-reviewed journals.

潮汐破裂事件（TDEs）是当星星被超大质量黑洞的引力场摧毁时发生的事件，它是对静止的超大质量黑洞性质的独特探索。到目前为止，已经观察到其中大约30个，而且随着调查和新仪器的上线，这个数字还在稳步增加。尽管我们拥有丰富的观测知识，但我们对TDE物理的理解，最终将使我们能够解释这些观测结果，充其量仍然是基本的。特别是，我们仍然不知道是什么原因导致碎片失去能量和角动量，落入黑洞并辐射。该项目将利用这样一个事实，即在其核心，TDE最终是由广义相对论磁流体动力学（GRMHD）运动方程很好地描述。通过对TDE进行直接的GRMHD模拟，该项目希望获得对TDE物理学的第一原理理解。拟议的模拟将提供几个长期存在的问题在TDE社区的答案：碎片如何循环，耗散能量，并acceptedonto SMBH？有多少恒星气体形成了这个盘，有多少气体作为流出物被喷射出来，这些气体如何依赖于黑洞的质量、自旋和恒星轨道的倾角？偏心吸积盘形成了吗？在这样的吸积盘中角动量是如何输运的？如果这样一个偏心盘是倾斜的，就像在TDEs中自然预期的那样，它会经历广义相对论性的进动吗？这样的圆盘会产生相对论性喷流吗？了解这些问题将使社区能够对TDE观测做出有意义的定量解释。尽管该项目专注于TDE，但它阐明了倾斜吸积盘及其喷流的基本物理学，适用于一系列源，包括类星体，黑洞双星和超亮X射线源。此外，拟进行的模拟将首次从第一性原理出发，研究偏心倾斜吸积盘中磁旋转不稳定性的发展以及这种盘在碎片流持续供给下的长期演化和GR进动。此外，被黑洞撕碎并产生相对论喷流的恒星提供了广义相对论的一些最迷人的表现。该项目将通过公开讲座、暑期学校、广播电台和报纸采访以及新闻稿传播作为该提案一部分所取得的成果。最后，该项目将涉及数据分析和可视化的本科生，他们将获得与大数据，黑洞吸积和喷流物理学合作的经验，在会议上展示他们的结果，并在同行评议的期刊上发表他们的工作。