Khodadi Mohsen, Vagnozzi Sunny, Firouzjaee Javad T
Department of Physics, K. N. Toosi University of Technology, P. O. Box 15875-4416, Tehran, Iran.
Department of Physics, University of Trento, Via Sommarive 14, 38123, Povo, TN, Italy.
Sci Rep. 2024 Nov 6;14(1):26932. doi: 10.1038/s41598-024-78264-y.
Mimetic gravity has gained significant appeal in cosmological contexts, but static spherically symmetric space-times within the baseline theory are highly non-trivial: the two natural solutions are a naked singularity and a black hole space-time obtained through an appropriate gluing procedure. We study the shadow properties of these two objects, finding both to be pathological. In particular, the naked singularity does not cast a shadow, whereas the black hole casts a shadow which is too small. We argue that the Event Horizon Telescope images of M87[Formula: see text] and Sgr A[Formula: see text] rule out the baseline version of mimetic gravity, preventing the theory from successfully accounting for the dark sector on cosmological scales. Our results highlight an interesting complementarity between black hole imaging observations and modified gravity theories of cosmological interest.
模拟引力在宇宙学背景下已获得显著关注，但基线理论中的静态球对称时空非常复杂：两个自然解分别是裸奇点和通过适当拼接过程得到的黑洞时空。我们研究了这两个物体的阴影特性，发现它们都存在问题。特别是，裸奇点不会产生阴影，而黑洞产生的阴影太小。我们认为，对M87和人马座A的事件视界望远镜图像排除了模拟引力的基线版本，使得该理论无法成功解释宇宙学尺度上的暗物质部分。我们的结果凸显了黑洞成像观测与具有宇宙学意义的修正引力理论之间有趣的互补性。
