Black-Hole Shadow Has Infinite Optical Depth

作者：Fukue Jun^*

来源：Publications of the Astronomical Society of Japan, 2011, 63(5): L53-L55.

• accretion
• accretion disks
• black hole physics
• Galaxy: center
• radiative transfer
• relativity

When a black hole is surrounded by a geometrically thin standard disk, we would observe a black-hole silhouette, whose edge is an innermost stable circular orbit. When it is surrounded by a geometrically thick supercritical disk, the central black hole would be self-occulted by the disk itself and massive winds. When it is covered by an optically thin plasma, on the other hand, a black-hole shadow would be seen, and observations of the black-hole shadow is now desired. If the optically thin plasma is freely infalling, however, we find that the optical depth in the radial direction becomes infinite due to the relativistic effect. Hence, the physical meanings of the black-hole shadow should be re-interpreted, although the shadow would be seen.

• 出版日期2011