The Event Horizon Telescope (EHT), a global very long baseline interferometry array operating at millimetre wavelengths, is spatially resolving the immediate environments of black holes for the first time. The current observations of the Galactic center black hole, Sagittarius A* (Sgr A*), and M87 have been interpreted in terms of either geometric models (e.g., a symmetric Gaussian) or detailed calculations of the appearance of black hole accretion flows. The former are not physically motivated, while the latter are subject to large systematic uncertainties. Motivated by the dominant relativistic effects of Doppler beaming and gravitational lensing in many calculations, we propose a geometric crescent model for black hole images. We show that this simple model provides an excellent statistical description of the existing EHT data of Sgr A* and M87, superior to other geometric models for Sgr A*. It also qualitatively matches physically predicted models, bridging accretion theory and observation. Based on our results, we make predictions for the detectability of the black hole shadow, a signature of strong gravity, in future observations.
Reshaping the inner shadow of a Kerr black hole by a torn accretion disk
School of Mathematics and Physics, University of South China（南华大学数学与计算学院）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Department of Mechanics, Chongqing Jiaotong University（重庆交通大学力学系）
Using horizon shadows to distinguish a black hole and a white hole
College of Science, Northeast Forestry University（东北林业大学理学院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences（中国科学院大学杭州高等研究院基础物理与数学学院）
Geometric Search for Hawking Radiation from Nearby Primordial Black Holes
School of Physics and Electronic Science, Guizhou Normal University（贵州师范大学物理与电子科学学院）；Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理重点实验室）；University of Chinese Academy of Sciences, Chinese Academy of Sciences（中国科学院大学）
New closed analytical solutions for geometrically thick fluid tori around black holes: Numerical evolution and the onset of the magneto-rotational instability
Shadow and Thermodynamics of deformed Schwarzschild-AdS black hole with a Cloud of Strings embedded in Perfect Fluid Dark Matter
The Assam Royal Global University（阿萨姆皇家全球大学）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）；Università di Roma “La Sapienza”（罗马第一大学）；Al-Farabi Kazakh National University（阿尔法拉比哈萨克国立大学）
