Description
The launch of relativistic jets of plasma on astrophysical to cosmological scales is observed in a variety of astrophysical sources. 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.
In this talk, I will review a first attempt to analytically study the motion of charged particles in the magnetosphere of the Kerr black hole. I will first review several key notions for the extraction of energy from a rotating black hole: (i) the amount of accessible spinning energy one can extract from a Kerr black hole, (ii) the variety of models to extract energy, and (iii) the basic of the Blandford-Znajek model and its limitations. Then, I will review under which conditions one can solve the motion of charged particles in a magnetized Kerr black hole which is the ket target of an analytic kinetic approach. I will use this opportunity to review (i) the integrability of the geodesic motion (for neutral particles) in the Kerr geometry and (ii) under which condition this result can be extended to the motion of charged particles for specific magnetosphere models. Based on this review, I will present a model where the motion of charged particles and their ejection can be studied fully analytically. This will allows us to show that (i) the radial acceleration is triggered by both the rotation of the black hole and its magnetization, (ii) the existence of a new magnetic frame-dragging effect dominating the standard Lense-Thirring effect, and (iii) that at a given spin, there is a critical magnetization threshold allowing charged particles to be accelerated (i.e. observed as blueshifted for an asymptotic observer) and finally (iv), that these particles can be accelerated only in a specific region whose maximal radius depends on the spin and magnetization of the black hole. Possible generalizations to more complex magnetosphere black hole models, and to neutrons stars will be discussed.