标题： M87黑洞阴影超出第一后牛顿阶的引力检验 显示英文标题

标题： Gravitational Test Beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole

摘要： 2017年事件视界望远镜（EHT）对M87星系中心源的观测首次测量了黑洞阴影的大小。这一观测为强场区域中的黑洞度规提供了一种新的且清晰的引力检验方法。我们通过解析方法证明，偏离克尔度规但满足弱场测试的空间时间会导致预测的黑洞阴影出现较大的偏差，这些偏差甚至与当前的EHT测量结果不一致。我们利用正则、参数化、非克尔度规的数值计算，识别出这些不同参数化共同具有的特性，该特性控制着预测的阴影大小。我们表明，阴影大小的测量对控制每个度规第二后牛顿项及其更高阶次的偏差参数施加了重要的限制，因此这些参数无法通过弱场测试来检测。这些新约束条件与由恒星质量源产生的引力波观测所施加的约束条件是互补的。 显示英文摘要

摘要： The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.