Gravitation and Black Hole Electrodynamics

Utah State University, Logan UT

Investigators

Abstract

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.