Realistic Simulations of Collisionless Black Hole Accretion Flows

无碰撞黑洞吸积流的真实模拟

基本信息

批准号：
1715061
负责人：
Feryal Ozel
金额：
$ 51.94万
依托单位：
University of Arizona
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-08-15 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1715061&HistoricalAwards=false
关键词：
Realistic Simulations Collisionless Black Hole

项目摘要

This project will be the first realistic study of an important type of flow onto black holes, of special interest in astrophysics. These particular flows, which are very hot but not very dense, have mostly been treated using methods whose assumptions are wrong for this particular combination of conditions. This work will start from first principles to include the important physics at both small and large scales in new numerical calculations. Junior researchers will learn about cutting edge techniques, which also help to drive the development of computer hardware and software systems.Accretion flows around nearby supermassive black holes contain hot and diffuse plasmas where the collisional mean free path is larger than the system size and the dissipative effects determine their thermodynamic and observational properties. Most theoretical models of these accretion flows are based on ideal magnetohydrodynamics (MHD), which is a collisional fluid theory. However, a number of assumptions in this formulation break down in hot, low luminosity accretion flows around black holes. This project is a first-principles computational and theoretical study with a focus on energy dissipation, transport, and particle acceleration. It uses firstly a general relativistic geodesic algorithm designed to integrate both photon and particle geodesics, and optimized for special-purpose architectures such as graphical processing units (GPUs). Massive scale gyrokinetic simulations will study both particle-level and global-level characteristics of hot, turbulent, collisionless plasmas. Secondly, a particle-in-cell code will be used for simulations focused on the microphysics of the plasma. This will study particle acceleration in current sheets in magnetic reconnection regions of the MHD simulations to quantify non-ideal effects and include the results in hydrodynamic and spectral studies of low radiative efficiency accretion flows.One graduate student will be trained and a postdoctoral associate will be supervised in computational, theoretical, and plasma astrophysics. The study's use of NSF-supported GPU computational resources will help to maintain cutting edge technology development in the United States, and the particle integrator algorithm will be made publicly available. The researchers will also run an extensive outreach effort, with public talks, popular articles, and documentaries.

该项目将是对在天体物理学特别感兴趣的黑洞流向的重要类型的现实研究。这些特殊的流非常热但不是很密集，主要是使用这种特定条件组合的假设错误的方法来处理的。这项工作将从第一原则开始，以在新的数值计算中包括小规模和大尺度的重要物理。初级研究人员将学习有关尖端技术的知识，这也有助于推动计算机硬件和软件系统的开发。附近的超级质量黑洞周围含有热和弥漫性等离子体，其中碰撞平均均值自由路径大于系统大小，并且耗散效果决定了其热力学和观测特性。这些积聚流的大多数理论模型都是基于理想的磁流失动力学（MHD），这是碰撞流体理论。但是，此公式中的许多假设在围绕黑洞的热，低亮度积聚中分解。该项目是一项原理计算和理论研究，侧重于耗能，传输和粒子加速度。它首先使用旨在整合光子和粒子大地测量学的一般相对论地理算法，并针对特殊用途体系结构（例如图形处理单元（GPU））进行了优化。大规模的陀螺仪模拟将研究热，湍流，无碰撞等离子体的粒子水平和全球级别特征。其次，将使用细胞中的粒子代码用于集中于等离子体的微物理学的模拟。这将研究MHD模拟的磁重新连接区域的电流表中的粒子加速度，以量化非理想效应，并包括对低辐射效率积聚流的水动力和光谱研究的结果。一个研究生将接受培训，并将在计算，理论，等立的计算，理论，理论和等立的计算学后协会。该研究对NSF支持的GPU计算资源的使用将有助于维持美国的尖端技术开发，并且将公开提供粒子积分算法。研究人员还将进行广泛的宣传工作，并进行公开谈判，流行文章和纪录片。