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

黑洞是宇宙中最神秘的物体。它们是物质在重力的作用下崩塌而形成的，产生了无限密度的奇点。这种奇点不能被直接观察到，因为它被视界所包围，黑洞的引力场如此之强，以至于连光都无法逃脱，但原则上可以观察到视界之外的物质。2019年4月10日，事件视界望远镜(EHT)成功拍摄到位于距离地球5500万光年的M87星系中心的首张黑洞图像。观测到的在巨大引力下弯曲的光环令人震惊地证实了超大质量黑洞存在于星系的中心。EHT的结果使科学家能够验证爱因斯坦在黑洞边界的引力理论的关键预测，并研究超大质量黑洞如何主导星系中心的能量学和动力学。这个项目的目的是通过改进EHT，在这一成功的基础上再接再厉，以便天文学家能够拍摄更详细的黑洞图像，并迈出制作黑洞电影的第一步。根据该奖项进行的观测将解决有关广义相对论和天文学的关键问题，包括黑洞是否自转，以及它们如何发射强大的喷流，这些喷流以接近光速的速度飞行到比宿主星系本身更远的距离。该项目包括培训下一代射电天文学家的资源，这些射电天文学家涉及美国大学(包括少数族裔服务机构)的博士后学者和研究生和本科生，并将向夏威夷社区进行文化推广。该奖项支持增强型事件视界望远镜(EHT)在未来三年继续运行，以测试广义相对论并研究超大质量黑洞的天体物理，包括银河系中心源(人马座A*)和附近星系M87中心的黑洞。在将亚毫米VLBI转换为跨异类阵列的标准观测模式的仪器方面的投资将使在最佳观测条件下触发的监测活动成为可能，从而能够研究M87喷气式飞机底部的材料动力学。将观测范围扩展到345 GHz频段将提高EHT的角分辨率，由于星际散射减少，它将锐化对射手座A*的看法，增强其研究这些来源和其他来源中磁场结构的能力，并检验光子环与观测频率无关的预测。EHT将继续通过年度征集建议的方式提供给更广泛的天文社区。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.