The Event Horizon Telescope: Resolving Black Holes in Time and Space

黑洞是宇宙中最神秘的物体。它们是物质在重力作用下自我坍缩，产生无限密度奇点时形成的。这个奇点不能被直接观察到，因为它被视界所包围，在视界处黑洞的引力场非常强，甚至光都无法逃脱，但原则上可以观察到视界外的物质。2019年4月10日，事件视界望远镜（EHT）成功地在距离地球5500万光年的M87星系中心拍摄了第一张黑洞图像。观测到的光环在巨大的引力下弯曲，令人震惊地证实了超大质量黑洞存在于星系中心。EHT的结果使科学家能够验证爱因斯坦黑洞边界引力理论的关键预测，并研究超大质量黑洞如何支配星系中心的能量学和动力学。这个项目的目标是在这个成功的基础上改进EHT，这样天文学家就可以制作更详细的黑洞图像，并迈出制作黑洞电影的第一步。该奖项下的观测将解决广义相对论和天文学的关键问题，包括黑洞是否旋转，以及它们如何发射强大的射流，以接近光速的速度飞行到比宿主星系本身更大的距离。该项目包括培训下一代射电天文学家的资源，包括博士后学者和美国大学的研究生和本科生，包括少数民族服务机构，并将对夏威夷社区进行文化推广。该奖项支持在未来三年内继续运行增强型事件视界望远镜（EHT），以测试广义相对论并研究超大质量黑洞的天体物理学，包括银河系中心源（人马座A*）和附近星系M87中心的黑洞。将亚毫米VLBI转换为跨异质阵列的标准观测模式的仪器投资将使在最佳观测条件下触发的监测活动成为可能，从而允许对M87喷气机底部材料的动力学进行研究。将观测扩展到345 GHz频段将提高EHT的角分辨率，由于星际散射的减少，将使其对人马座A*的视野更加清晰，增强其研究这些和其他源磁场结构的能力，并验证光子环与观测频率无关的预测。EHT将继续通过年度提案征集向更广泛的天文学界开放。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Black holes are the most mysterious objects in the cosmos. They are formed when matter collapses in on itself under the force of gravity, producing a singularity of infinite density. This singularity cannot be directly observed because it is surrounded by an event horizon, the point where the black hole’s gravitational field is so strong that even light cannot escape, but matter outside the event horizon can in principle be observed. On April 10, 2019, the Event Horizon Telescope (EHT) succeeded in producing the first image of a black hole at the center of the galaxy M87, 55 million light years from Earth. The observed ring of light bent in the immense gravity was stunning confirmation that supermassive black holes exist in the centers of galaxies. The EHT results enabled scientists to verify key predictions of Einstein’s theory of gravity at the black hole boundary and to study how supermassive black holes dominate the energetics and dynamics at the centers of galaxies. This project aims to build upon this success by improving the EHT so that astronomers can make black hole images that are much more detailed and take the first steps towards making black hole movies. Observations under this award will address key questions about general relativity and astronomy, including whether black holes spin and how they launch powerful jets that travel at nearly the speed of light to distances larger than the host galaxy itself. This project includes resources for training the next generation of radio astronomers involving postdoctoral scholars and graduate and undergraduate students at US universities, including minority-serving institutions, and will undertake cultural outreach to the Hawaiian community.This award supports continued operations of an enhanced Event Horizon Telescope (EHT) over the next three years to test general relativity and study the astrophysics of supermassive black holes, including the Galactic Center source (Sagittarius A*) and the black hole in the center of the nearby galaxy M87. Investments in instrumentation to transform submillimeter VLBI into a standard observing mode across the heterogeneous array will enable monitoring campaigns triggered during optimal observing conditions, allowing a study of the dynamics of the material at the base of the jet in M87. The extension of observing to the 345 GHz frequency band will increase the angular resolution of the EHT, sharpen its view of Sagittarius A* due to reduced interstellar scattering, enhance its ability to study the structure of the magnetic field in these and other sources, and test the prediction that photon rings are independent of observing frequency. The EHT will continue to be made available to the broader astronomical community through an annual call for proposals.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.