Description
The launch of relativistic jets of plasma on astrophysical to cosmological scales is observed in a variety of astrophysical sources, from active galactic nuclei to X-ray binaries. While these jets can be reproduced by general relativistic magneto-hydrodynamics (GRMHD) and particle-in- cells (GRPIC) simulations of the dynamical Kerr magnetosphere, the development of analytic models to describe the physics of the jets has remained limited. A key challenge is to analytically describe the individual trajectories of accelerated charged particles, which ultimately build up the jet and emit radiation. In this talk, I will review a first simple but fully analytical model of jet launching from the Kerr magnetosphere based on the motion of charged particles. To that end, I will review the condition for the integrability of electrogeodesic motion in the Kerr monopole magnetosphere allowing one to study the ejection of charged particles near the poles. Based on this, I will discuss (i) a criterion for the rotation axis to constitute a stable latitudinal equilibrium position, thereby representing an idealized jet, (ii) the expression for the magnetic frame-dragging effect, and (iii) the condition for an asymptotic observer to measure blueshifted particles emanating from the black hole surroundings. This will show that particles can be accelerated only in a specific region whose maximal radius depends on the spin and magnetization of the black hole. Alongside these results, I will review the role of the explicit and hidden symmetries when building models for the Kerr magnetosphere.
Based on: https://arxiv.org/abs/2601.05048