Gravitation and Black Hole Electrodynamics

相对论喷流是天体物理系统演化的核心，从恒星尺度到星系尺度。确定在快速旋转的黑洞边缘产生物质流动的机制，以及电磁场如何在空间中产生和组织，可以显著提高我们在数学物理、万有引力和天体物理学方面的知识。最近的测量表明，自然界中存在近乎极端（即几乎以最大理论极限旋转）的黑洞，因此在未来的天体物理实验中可以探测到近乎极端的黑洞。Blandford-Znajek （BZ）模型——一种从旋转黑洞中提取电磁能量的机制——被认为是最有希望解释在类星体中观测到的能量的框架，正如数值模拟所表明的那样，这是从旋转黑洞中提取能量的最有效方法。尽管有这些发现，很少有理论工作系统地解决了（近）极端黑洞的BZ能量提取机制，并且仍然难以直观地描述电磁场如何在空间中产生和组织。这个项目的总体目标是改变这种情况。该奖项支持克尔黑洞附近相对论性流出机制的研究。首先，通过构建电磁场的作用原理，为BZ模型提供一个一般的理论框架。其次，通过定义（近）极值黑洞边缘的解空间和运算域，研究黑洞能量提取的成因；最后，它将通过寻找新发现的纯电磁版本的BZ过程的扩展和新解决方案，开发一个直观的电磁能量和电荷电流的流动如何在空间中起源和组织的图像。实现这些目标将为研究强场体系下的广义相对论和黑洞边缘的流出过程打开一扇新的窗口。结合即将获得的前所未有的观测数据，目前的跨学科理论研究有可能从根本上提高我们对基础理论的认识，并影响旋转黑洞的天文测量。

Relativistic jets are central to the evolution of astrophysical systems, from stellar to galactic scales. Identifying the mechanisms that generate matter flows at the edge of rapidly rotating black holes and how the electromagnetic fields originate and organize in space can significantly advance our knowledge in mathematical physics, gravitation, and astrophysics. Recent measurements suggest that nearly extremal (i.e., spinning at almost the maximum theoretical limit) black holes exist in nature, and consequently nearly extremal black holes could be detected in future astrophysical experiments. The Blandford-Znajek (BZ) model - a mechanism for electromagnetic energy extraction from a rotating black hole - is considered to be the most promising framework to explain the energy observed in quasars and, as the numerical simulations indicate, the most efficient way to extract energy from a rotating black hole. In spite of these findings, few theoretical works have systematically addressed the BZ energy extraction mechanisms for (near-)extremal black holes, and it still remains difficult to develop an intuitive picture of how the electromagnetic fields originate and organize in space. It is the overall aim of this project to amend this situation.This award supports research on relativistic outflow mechanisms near Kerr black holes. Firstly, it will provide BZ models with a general theoretical framework by constructing an action principle for the electromagnetic fields. Secondly, it will study the genesis of energy extraction in black hole by defining the solution space and domain of operation at the edge of (near-)extreme black holes. Lastly, it will develop an intuitive picture of how the flow of electromagnetic energy and charge current originates and organizes in space by finding extensions and novel solutions of the newly discovered purely electromagnetic version of the BZ process. Realizing these proposed goals will open a new window on the study of general relativity in the strong field regime and outflow processes at the edge of black holes. Combined with the unprecedented observational data that will soon become available the present interdisciplinary theoretical research has the potential to radically enhance our knowledge of the fundamental theory and to impact the astronomical measurements of spinning black holes.