Pushed by a number of advances, electromagnetic observatories have now reached the horizon scale of supermassive black holes. The existence and properties of horizons in our universe is one of the outstanding fundamental issues that can now be addressed. Here we investigate the ability to discriminate between black holes and compact, horizonless objects, focusing on the lensing of hot spots around compact objects. We work in particular with boson and Proca stars as central objects, and show that the absence of a horizon gives rise to a characteristic feature—photons that plow through the central object and produce an extra image. This feature should be universal for central objects made of matter weakly coupled to the standard model.

中文翻译：

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围绕无水平天体运行的热点的观测特征

在一系列进步的推动下，电磁观测站现在已经达到了超大质量黑洞的视界尺度。我们宇宙中视界的存在和性质是现在可以解决的突出的基本问题之一。在这里，我们研究了区分黑洞和紧凑、无视界物体的能力，重点关注紧凑物体周围热点的透镜效应。我们特别将玻色子和普罗卡星作为中心天体进行研究，并表明没有地平线会产生一个特征——光子穿过中心天体并产生额外的图像。对于由弱耦合到标准模型的物质构成的中心物体，该特征应该是通用的。