The Theory and Simulation of Relativistic Jet Formation: Towards a Unified Model For Micro- and Macroquasars

Abstract

I review recent progress in the theory of relativistic jet production, with special emphasis on unifying black hole sources of stellar and supermassive size. Observations of both classes of objects, as well as theoretical considerations, indicate that such jets may be launched with a spine/sheath flow structure, having a much higher Lorentz factor ($\sim 50$) near the axis and a lower speed ($\Gamma \sim 10$ or so) away from the axis. It has become clear that one can no longer consider models of accretion flows without also considering the production of a jet by that flow. Furthermore, the rotation rate of the black hole also must be taken into account. It provides a third parameter that should break the mass/accretion rate degeneracy and perhaps explain why some sources are radio loud and some radio quiet. Slow jet acceleration and collimation is expected theoretically, and can explain some of the observed features of AGN jet sources. Finally, relativistic jets launched by MHD/ED processes are Poynting flux dominated by nature, and are potentially unstable if there is significant entrainment of thermal material.