The Shadow of a Spherically Accreting Black Hole
The Shadow of a Spherically Accreting Black Hole
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DOI：
10.3847/2041-8213/ab518c
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
R. Narayan;Michael D. Johnson;C. Gammie
中科院分区：
文献类型：
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作者：
R. Narayan;Michael D. Johnson;C. Gammie
我们探讨了一个简单的球模型的史瓦西黑洞的光学薄吸积，并研究了图像的性质，看到一个遥远的观察者。我们表明，一个黑暗的圆形区域的中心，一个阴影，总是存在的。阴影的外缘位于光子环半径处，其中是吸积质量M的引力半径。阴影边缘的位置与吸积气体停止辐射的内半径无关。因此，观测到的阴影的大小是时空几何的一个特征，它几乎不受吸积细节的影响。我们简要地讨论了这些结果的相关性的事件视界望远镜图像的超大质量黑洞在M87。
We explore a simple spherical model of optically thin accretion on a Schwarzschild black hole, and study the properties of the image as seen by a distant observer. We show that a dark circular region in the center—a shadow—is always present. The outer edge of the shadow is located at the photon ring radius , where is the gravitational radius of the accreting mass M. The location of the shadow edge is independent of the inner radius at which the accreting gas stops radiating. The size of the observed shadow is thus a signature of the spacetime geometry and it is hardly influenced by accretion details. We briefly discuss the relevance of these results for the Event Horizon Telescope image of the supermassive black hole in M87.