标题： 具有普适视界的非超曲面正交性 显示英文标题

标题： Universal Horizons without Hypersurface Orthogonality

摘要： 洛伦兹破缺引力的一个关键后果是修正色散关系的出现，这暗示了不存在普遍的最大传播速度。 这挑战了事件视界作为所有自由度共同因果边界的传统概念。 然而，在这些理论中的某些解表现出\emph{普遍地平线}—— 即能够捕获任意高速信号的表面，从而恢复黑洞的概念。 先前的研究已经广泛研究了在洛伦兹破缺通过超曲面正交\ae{}场编码的情况下普遍视界的特性。 在这项工作中，我们探讨了将这一概念扩展到更一般的情况的可能性，其中超曲面正交性被放松。 为此，我们构造了一个候选捕获表面，并使用洛伦兹破缺物质的一般模型分析其因果属性。 我们发现，除了与普遍视界相关的标准条件外，\ae{}场的扭曲局部为零也是必要的。 然后，我们通过适当地变形爱因斯坦-\ae{}场理论中最近发现的“幽灵”克尔解中的\ae{}场流，给出了这样一个普遍视界的明确例子。 此外，我们分析了在普遍视界处非解析的轨迹的行为，并讨论了我们的发现对霍金辐射的影响。 尽管我们的分析是基于爱因斯坦-\ae{t}场引力激发的，但我们的结果适用于更广泛的洛伦兹破缺理论类，进一步支持了这些框架下黑洞现象学的相关性。 显示英文摘要

摘要： A key consequence of Lorentz-violating gravity is the emergence of modified dispersion relations implying the absence of a universal maximum propagation speed. This challenges the conventional notion of the event horizon as a causal boundary common to all degrees of freedom. However, certain solutions in these theories exhibit \emph{universal horizons} -- surfaces capable of trapping signals of arbitrarily high speed, thereby restoring the notion of black hole. Previous studies have extensively characterised universal horizons in settings where Lorentz violation is encoded via a hypersurface-orthogonal \ae{}ther. In this work, we explore the possibility of extending this concept to more general cases where hypersurface orthogonality is relaxed. To do so, we construct a candidate trapping surface and analyse its causal properties using a general model for Lorentz-violating matter. We find that, in addition to the standard conditions associated to universal horizons, a local vanishing of the \ae{}ther's twist is also necessary. We then provide an explicit example of such a universal horizon by suitably deforming the \ae{}ther flow in a stealth Kerr solution recently found in Einstein--\ae{}ther theory. Moreover, we analyse the behaviour of trajectories which are not analytical at the universal horizon and discuss the implications of our findings for Hawking radiation. While our analysis is motivated by Einstein-\ae{t}her gravity, our results apply to broader classes of Lorentz-violating theories, further supporting the relevance of black hole phenomenology in these frameworks.