近日，日本京都大学Koga, Yasutaka团队研究了AdS重力星和体锥奇点。该研究成果发表在2025年7月17日出版的《高能物理杂志》上。

黑洞的视界被光子球包围，外部观察者很难观察到光子球内部的几何形状。

研究组提出了一种以AdS/CFT对应为主题的对偶共形场理论来研究区域的方法。他们首先将重力星几何构造为渐近反德西特时空，其中光子球内的区域被无视界几何所取代。

已知对偶共形场论中延迟格林函数的体锥奇点可以编码体零测地线。然后，研究组从体理论中数值计算延迟的格林函数，并观察到传播到内部区域的零测地线对应的体锥奇点。通过这种方法，研究组证明了从对偶共形场理论的体锥奇点来考察光子球内部区域是可能的。

附：英文原文

Title: AdS gravastar and bulk-cone singularities

Author: Chen, Heng-Yu, Hikida, Yasuaki, Koga, Yasutaka

Issue&Volume: 2025-07-17

Abstract: The horizon of black hole is surrounded by the photon sphere and an outside observer cannot easily examine the geometry inside the photon sphere. In this note, we propose a way to investigate the region from dual conformal field theory by making use of AdS/CFT correspondence. We first construct gravastar geometry as an asymptotic anti-de Sitter spacetime, where the region inside the photon sphere is replaced by a horizon-less geometry. It is known that bulk-cone singularities in the retarded Green function in dual conformal field theory can encode the bulk null geodesics. We then compute numerically the retarded Green function from the bulk theory and observe bulk-cone singularities corresponding to null geodesics traveling into the interior region. In this way, we show that it is possible to examine the region inside the photon sphere from bulk-cone singularities of dual conformal field theory.

DOI: 10.1007/JHEP07(2025)199

Source: https://link.springer.com/article/10.1007/JHEP07(2025)199