Neutron stars and black holes are the astrophysical systems with the strongest gravitational fields in the universe. In this article, I review the prospect of using observations of such compact objects to probe some of the most intriguing general relativistic predictions in the strong-field regime: the absence of stable circular orbits near a compact object and the presence of event horizons around black-hole singularities. I discuss the need for a theoretical framework, within which future experiments will provide detailed, quantitative tests of gravity theories. Finally, I summarize the constraints imposed by current observations of neutron stars on potential deviations from general relativity.

中文翻译：

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通过电磁波谱观测进行强场重力探测和测试。

中子星和黑洞是宇宙中引力场最强的天体物理系统。在本文中，我回顾了利用对此类致密天体的观测来探索强场状态下一些最有趣的广义相对论预测的前景：致密天体附近不存在稳定的圆形轨道，并且黑色周围存在事件视界- 孔奇点。我讨论了对理论框架的需求，未来的实验将为引力理论提供详细的定量测试。最后，我总结了当前中子星观测对广义相对论潜在偏差的限制。