论文标题
固定的黑洞和灯环
Stationary black holes and light rings
论文作者
论文摘要
天体重要的Kerr黑洞（BH）的响声和阴影都与一组特殊的绑定的零轨道密切相关，称为轻环（LRS）。是否认为通用平衡BH必须具有这样的轨道？在这封信中，我们证明了以下定理。一个固定的，Axi对称的，渐近平坦的黑洞时空，在1+3个维度中，具有非超级，拓扑的球形，杀戮地平线，至少在每种旋转感的地平线以外的一个标准LR承认。证明依赖于拓扑论点，并假定$ c^2 $ - 平滑度和圆形性，但不使用字段方程。该论点还适用于恢复以前的定理，以确定无水平的超紧凑对象必须接受均匀数量的非分类LR，其中之一是稳定的。
The ringdown and shadow of the astrophysically significant Kerr Black Hole (BH) are both intimately connected to a special set of bound null orbits known as Light Rings (LRs). Does it hold that a generic equilibrium BH must possess such orbits? In this letter we prove the following theorem. A stationary, axi-symmetric, asymptotically flat black hole spacetime in 1+3 dimensions, with a non-extremal, topologically spherical, Killing horizon admits, at least, one standard LR outside the horizon for each rotation sense. The proof relies on a topological argument and assumes $C^2$-smoothness and circularity, but makes no use of the field equations. The argument is also adapted to recover a previous theorem establishing that a horizonless ultra-compact object must admit an even number of non-degenerate LRs, one of which is stable.
