Black Holes are possibly the most enigmatic objects in our universe. From their detection in gravitational waves upon their mergers, to their snapshot eating at the centres of galaxies, black hole astrophysics has undergone an observational renaissance in the past four years. Nevertheless, they remain active playgrounds for strong gravity and quantum effects, where novel aspects of the elusive theory of quantum gravity may be hard at work. In this review article, we provide an overview of the strong motivations for why “Quantum Black Holes” may be radically different from their classical counterparts in Einstein’s General Relativity. We then discuss the observational signatures of quantum black holes, focusing on gravitational wave echoes as smoking guns for quantum horizons (or exotic compact objects), which have led to significant recent excitement and activity. We review the theoretical underpinning of gravitational wave echoes and critically examine the seemingly contradictory observational claims regarding their (non-)existence. Finally, we discuss the future theoretical and observational landscape for unraveling the “Quantum Black Holes in the Sky”.

中文翻译：

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天空中的量子黑洞

黑洞可能是我们宇宙中最神秘的物体。从他们合并后的引力波探测到在银河系中心的吞噬快照，黑洞天体物理学在过去四年中经历了观测复兴。然而，它们仍然是活跃的运动场，以产生强大的引力和量子效应，其中难以捉摸的量子引力理论的新颖方面。在这篇评论文章中，我们概述了为什么“量子黑洞”可能与爱因斯坦广义相对论中的经典对应词根本不同的强烈动机。然后，我们讨论量子黑洞的观测特征，重点关注引力波回波作为量子视界（或奇异的紧凑物体）的吸烟枪，这导致了最近的重大兴奋和活动。我们回顾了重力波回波的理论基础，并严格审查了关于它们（不存在）的看似矛盾的观测要求。最后，我们讨论了解开“量子黑洞在天空中”的未来理论和观察前景。