Gravity in the Galactic Center: Precise 3D Stellar Kinematics in the Inner Parsec

黑洞是研究引力的最佳实验室。在银河系的中心，有一个巨大的黑洞，其质量是太阳的四百万倍。黑洞周围的时空因其质量而弯曲，因其旋转而扭曲。该项目旨在通过监测围绕黑洞运行的特殊类型恒星的运动来研究银河系中心黑洞周围的变形时空。这些奇特的恒星发出明亮的射频激光（称为脉泽），射电望远镜可以非常精确地观察和测量。智利和新墨西哥州的射电望远镜将在三维空间上追踪这些脉泽星的运动，并绘制出离我们最近的大质量黑洞周围的时空。该项目的主要目标是研究银河系中心的重力，促进各级科学教育，并使这门科学向公众开放。研究人员测量了银河系中心几光年内恒星的位置、速度和加速度，因为它们对银河系中心的超大质量黑洞（SMBH）、恒星和恒星残骸的引力场做出了反应。这是通过使用美国国家科学基金会的阿塔卡马大型毫米/亚毫米阵列和甚大阵列对恒星大气一氧化碳（SiO）脉泽进行多普勒跟踪来完成的。通过一系列的观测，研究人员为围绕SMBH运行的恒星的红外观测提供了一个参考框架，并探测了暗恒星的残余种群。通过跟踪这些恒星，研究人员可以测量中心黑洞的旋转和质量，并测试等效原理、黑洞的“无毛”定理和框架拖拽。该项目将培养新的科学家，并在引力理论和观测研究之间建立协同作用。调查人员将把研究带入课堂和公共领域。本科生和研究生将直接参与研究，并与STEM领域传统上代表性不足的群体进行接触，包括少数民族、女性、第一代大学生和农村社区。一个大质量黑洞附近恒星运动的动画理论和观测可视化将为球体科学（SOS）计划开发，并分发给全球大约150个SOS装置。研究人员将使用科罗拉多州的Fiske天文馆作为开发测试平台，将可视化应用于数字天文馆的演示，并将其分发到所有数字设施，以获得最大的影响。这个项目将使引力、相对论和黑洞等广泛的概念能够向公众和K-12学校传播。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 best laboratories for studying gravity. In the center of our galaxy, the Milky Way, lies a massive black hole that weighs four million times the mass of our Sun. The spacetime around this black hole is curved by its mass and twisted by its rotation. This project aims to study the deformed spacetime around the Milky Way's central black hole by monitoring the motions of special types of stars orbiting the black hole. These peculiar stars emit bright radio-frequency lasers (called masers) that radio telescopes can observe and measure very precisely. Radio telescopes in Chile and New Mexico will track the motions of these maser stars in three dimensions and map out the spacetime around our nearest massive black hole. The main goals of this project are to study gravity in the center of our galaxy, to promote science education at all levels, and to make this science publicly accessible. The investigators measure the positions, velocities, and accelerations of stars in the central few light years of the Milky Way, as they react to the gravitational field of the supermassive black hole (SMBH), stars, and stellar remnants in the Galactic Center. This is done through Doppler tracking of stellar atmosphere silicon monoxide (SiO) masers using the NSF's Atacama Large Millimeter/submillimeter Array and the Very Large Array. With a series of observations, the investigators provide a reference frame for infrared observations of stars orbiting the SMBH and probe the dark stellar remnant population. By tracking these stars, the investigators can measure the spin and mass of the central black hole and test the equivalence principle, the "no-hair" theorem of black holes, and frame-dragging. This program will train new scientists and create synergy between theoretical and observational studies of gravity. The investigators will bring the research into the classroom and the public domain. Undergraduate and graduate students will be directly involved in the research and in outreach to traditionally under-represented groups in STEM fields, including minorities, women, first-generation college students, and rural communities. Animated theoretical and observational visualization of the motions of stars close to a massive black hole will be developed for the Science on a Sphere (SOS) program and distributed to the roughly 150 SOS installations worldwide. The investigators will adapt the visualizations for digital planetarium presentation, using Colorado's Fiske Planetarium as a development testbed, and distribute them to all digital facilities for maximum impact. This project will enable communication of the broad ideas of gravity, relativity and black holes to the public and to K-12 schools.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.