Collaborative Research: Experimental General Relativity using Radio Interferometry of a Black Hole Photon Ring

合作研究：利用黑洞光子环射电干涉测量的实验广义相对论

• 批准号: 2307887
• 负责人: Michael Johnson
• 金额: $ 26.82万
• 依托单位: Smithsonian Institution Astrophysical Observatory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307887&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; General; Relativity

In April 2019, the Event Horizon Telescope (EHT) collaboration released the first images of a black hole, a breakthrough result that has since prompted a flurry of new theoretical studies. These have revealed that black hole images carry distinctive relativistic signatures, which are embedded within a bright, narrow ring encircling the black hole. A research collaboration between the Smithsonian Institution Astrophysical Observatory and Vanderbilt University will explore the fundamental properties of this “photon ring,” will show how it can be studied using radio interferometry, and will determine the properties of a black hole’s spacetime that can be probed with observations. These researchers have already established the photon ring as a universal prediction of General Relativity: it is a matter-independent effect caused by the extreme bending of light near the event horizon of the black hole. Indeed, Einstein’s theory predicts that Kerr black holes can deflect light rays to such a degree that they circumnavigate the black hole—possibly several times—before eventually reaching distant observers. Black hole imaging is a nascent field with an already global reach and intense public engagement. As part of this project, the investigators will engage the public with this research through the development of new classroom activities for neurodiverse and special education students as well as novel art exhibits conveying the elegance and mysteries hidden within black hole images.During this project, scientists will study the information that the orbiting light encodes about the geometry of the black hole’s spacetime, as well as the astrophysical conditions of the surrounding plasma and electromagnetic fields. This will combine the pursuit of two parallel yet interconnected lines of work: 1) On the theory side, analysis of simple models will build intuition and provide insight into interferometric properties of the photon ring, while development of time- dependent, “slow-light” photon ring models with variability informed by plasma astrophysics will clarify how the simple models relate to the complex structure in a realistic accretion flow model; and 2) On the observational side, the development of progressively more elaborate statistical inference tools and numerical simulations will utilize these models to extract increasingly precise knowledge of supermassive black hole astrophysics from interferometric data, culminating in formal posteriors for the mass, spin, and inclination of both M87* and Sgr A* from EHT data.Two major research outputs of this project will be the comprehensive characterization of the unique photon ring signatures that can be targeted with VLBI (very-long-baseline interferometry), and model-agnostic estimates of mass, spin, and inclination for M87* and Sgr A* using current EHT data.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.

2019年4月，事件视界望远镜（EHT）合作发布了第一批黑洞图像，这一突破性结果引发了一系列新的理论研究。这些发现表明，黑洞图像带有独特的相对论特征，这些特征嵌入在环绕黑洞的明亮而狭窄的环中。史密森学会天体物理天文台和范德比尔特大学之间的一项研究合作将探索这个“光子环”的基本特性，将展示如何使用无线电干涉测量法研究它，并将确定黑洞时空的特性，这些特性可以通过观测来探测。这些研究人员已经将光子环作为广义相对论的普遍预测：它是由黑洞视界附近的光的极端弯曲引起的一种与物质无关的效应。事实上，爱因斯坦的理论预言，克尔黑洞可以将光线偏转到这样的程度，即光线在最终到达遥远的观测者之前，可能会绕黑洞几圈。黑洞成像是一个新兴的领域，已经遍及全球，公众参与也很强烈。作为该项目的一部分，研究人员将通过为神经多样性和特殊教育学生开发新的课堂活动以及新颖的艺术展览来吸引公众参与这项研究，展示隐藏在黑洞图像中的优雅和神秘。在这个项目中，科学家们将研究轨道光编码的有关黑洞时空几何的信息，以及周围等离子体和电磁场的天体物理条件。这将把两个平行但相互关联的工作结合起来：1)在理论方面，对简单模型的分析将建立直觉并提供对光子环干涉特性的见解，而发展时间依赖的“慢光”光子环模型与等离子体天体物理学的变异性将阐明简单模型如何与现实吸积流模型中的复杂结构相关联；2)在观测方面，越来越复杂的统计推断工具和数值模拟的发展将利用这些模型从干涉测量数据中提取越来越精确的超大质量黑洞天体物理学知识，最终从EHT数据中获得M87*和Sgr A*的质量、旋转和倾角的正式后检。该项目的两个主要研究成果将是利用VLBI（超长基线干涉测量）对独特的光子环特征进行综合表征，以及利用当前EHT数据对M87*和Sgr A*的质量、自旋和倾角进行模型无关的估计。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。