The Galactic Center Orbits Initiative: Probing the Physics & Astrophysics of the Closest Supermassive Black Hole

我们的银河系中心有一个超大质量黑洞（SMBH）。多年来，研究人员一直在观察围绕SMBH运行的单个恒星。研究人员利用这些观测结果研究了强引力和致密环境对这些恒星的影响。他们的观测表明，正如预期的那样，这些恒星在SMBH周围移动得非常快。研究人员发现，SMBH附近的环境是可以通过地球观测来研究的最极端的自然世界。这些观测与模型相结合，被用作理解支配我们宇宙的物理原理的实验室。研究人员计划使用世界上最大的望远镜进行进一步的观测，以寻找只有在极端环境中才能探测到的引力的新特性。通过对恒星运动的精确测量，研究人员已经确定了SMBH的大小和距离。到目前为止，他们的观察结果与爱因斯坦广义相对论的预测完全一致。他们新项目的目的是通过持续监测SMBH周围恒星的运动来完善他们的相对论测试。他们仔细测量恒星的位置偏离经典轨道描述的程度。他们将更精确地测量到银河系中心的距离，这决定了银河系的大小。此外，他们预计银河系中心密集的恒星会结合成双星，最终相互融合，产生新的恒星。有些最终会变成恒星大小的黑洞。研究人员向公众传达他们令人兴奋的研究成果，并吸引年轻人，特别是女性，从事科学和技术事业。该项目的目标是基于对尽可能靠近黑洞的众多恒星的轨道的精确测定。因为银河系中心的恒星密度非常高，所以尽可能高的空间分辨率的观测是必不可少的。该项目将在W.M.凯克天文台使用自适应光学望远镜。尽管研究人员已经获得了多年的数据，但这是一个长期的项目，因为轨道的周期从几十年到几百年不等。由于观测技术的不断改进，每增加一年的数据，轨道的准确性就会不成比例地提高。这些轨道还将被用来对黑洞周围暗物质的丰度和分布设定严格的限制，或者可能是测量。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。

Our Milky Way galaxy has a supermassive black hole (SMBH) at its center. The investigators have observed individual stars orbiting the SMBH for many years. The investigators use these observations study the effects of strong gravity and the dense environment on these stars. Their observations show the stars moving very fast around the SMBH, as expected. The investigators find the environment near the SMBH is the most extreme of the natural world that can be studied by observations from Earth. These observations, combined with models, are used as a laboratory for understanding the physical principles that govern our universe. The investigators plan further observations using the world's largest telescopes to search for new properties of gravity that can only be detected in extreme environments. Using precise measurements of the stars' motions, the investigators have determined the size and the distance of the SMBH. So far, their observations are exactly consistent with predictions of Einstein's general theory of relativity. The aim of their new project is to refine their tests of relativity by continued monitoring of the motions of stars around the SMBH. They carefully measure how much the stars' positions will stray from the classical description of their orbits. They will more precisely measure the distance to the Galactic center, which sets the size scale of the Galaxy. Furthermore, they expect the densely packed stars at the Galactic center to become joined as binary stars that could ultimately merge with each other to produce new kinds of stars. Some can ultimately become star-sized black holes. The investigators convey to the public the exciting results of their research and attract young people, particularly women, into careers in science and technology. The objectives of this project are based on precise determinations of the orbits of numerous stars located as close to the black hole as possible. Because the density of stars at the Galactic center is exceptionally high, observations with the highest possible spatial resolution are essential. This project will employ adaptive optics with 10m telescopes at the W.M. Keck Observatory. Although the investigators have already obtained many years of data, this is a long-term project because the periods of the orbits range from tens to hundreds of years. Each additional year of data increases the accuracy of the orbits disproportionately because of the constantly improving observational technologies. The orbits will also be used to set strong limits on, or possibly measure, the abundance and distribution of dark matter around the black hole.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.