ngEHT模型库黑洞数值模拟中的吸积流形态学：辐射物理的影响
Accretion Flow Morphology in Numerical Simulations of Black Holes from the ngEHT Model Library: The Impact of Radiation Physics
摘要：
在过去的几年里，事件视界望远镜（EHT）提供了有史以来第一个超大质量黑洞（BH）（M87*）和人马座A $^*$（Sgr A*）的事件视界尺度图像。下一代EHT项目是EHT阵列的扩展，它承诺更大的角分辨率和更高的灵敏度，对中心环状结构周围的暗淡，扩展的通量，可能连接吸积流和喷流。ngEHT分析挑战旨在了解从合成图像和电影中提取的科学可提取性，以告知ngEHT阵列设计和分析算法开发。在这项工作中，我们比较了吸积流结构和动力学的数值流体模拟，专门针对M87* 和Sgr A*，并被用来构建源模型的挑战集。我们考虑了（1）一个稳态轴对称的辐射无效吸积流模型，（2）两个含时单流体广义相对论磁流体动力学（GRMHD）的H-AMR程序模拟，（3）一个双温GRMHD的BHAC程序模拟，（4）一个双温辐射GRMHD的KORAL程序模拟。我们发现，不同的模型表现出显着相似的时间和空间特性，除了电子温度，因为辐射损失大幅冷却电子附近的BH和喷流鞘，信号的重要性，即使是缓慢吸积BH，如M87*。我们限制自己的标准环面吸积流，并留下更大的探索替代吸积模型，以未来的工作。
英文摘要：
In the past few years, the Event Horizon Telescope (EHT) has provided the first-ever event horizon-scale images of the supermassive black holes (BHs) (M87*) and Sagittarius A$^*$ (Sgr A*). The next-generation EHT project is an extension of the EHT array that promises larger angular resolution and higher sensitivity to the dim, extended flux around the central ring-like structure, possibly connecting the accretion flow and the jet. The ngEHT Analysis Challenges aim to understand the science extractability from synthetic images and movies to inform the ngEHT array design and analysis algorithm development. In this work, we compare the accretion flow structure and dynamics in numerical fluid simulations that specifically target M87* and Sgr A*, and were used to construct the source models in the challenge set. We consider (1) a steady-state axisymmetric radiatively inefficient accretion flow model with a time-dependent shearing hotspot, (2) two time-dependent single fluid general relativistic magnetohydrodynamic (GRMHD) simulations from the H-AMR code, (3) a two-temperature GRMHD simulation from the BHAC code, and (4) a two-temperature radiative GRMHD simulation from the KORAL code. We find that the different models exhibit remarkably similar temporal and spatial properties, except for the electron temperature, since radiative losses substantially cool down electrons near the BH and the jet sheath, signaling the importance of radiative cooling even for slowly accreting BHs such as M87*. We restrict ourselves to standard torus accretion flows, and leave larger explorations of alternate accretion models to future work.
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