Related papers: MHD accretion-ejection: jets launched by a non-iso…
We present steady-state calculations of self-similar magnetized accretion discs driving cold, adiabatic, non-relativistic jets. For the first time, both the magnetic torque due to the jets and a turbulent "viscous" torque are taken into…
We reexamine a previously proposed model for thermal pressure acceleration of collimated outflows in young stellar objects (YSO). We are motivated by new results from recent X-ray observations of YSO. These show that there is essentially no…
The most accepted model for jet production is based on the magneto-centrifugal acceleration out off an accretion disk that surrounds the central source (Blandford & Payne, 1982). This scenario, however, does not explain, e.g., the…
Axisymmetric magnetohydrodynamic (MHD) simulations have been applied to investigate the interrelation of a central stellar magnetosphere and stellar wind with a surrounding magnetized disk outflow and how the overall formation of a large…
We solve, and provide analytical expressions, for current-free magnetic configurations in the context of initial setups of 3-dimensional simulations of astrophysical jets involving an accretion disk corona in hydrostatic balance around a…
We present global magnetohydrodynamic (MHD) simulations of accretion disks with a strong toroidal magnetic field using an equation of state that fixes the gas thermal scale height. The disk forms from the inflow of a rotating magnetized gas…
In this lecture I review the theory of magnetized accretion discs driving jets, with a focus on Young Stellar Objects (YSOs). I first introduce observational and theoretical arguments in favor of the ``disc wind'' paradigm. There, accretion…
Strong magnetic fields modify particle motion in the curved space-time of spinning black holes and change the stability conditions of circular orbits. We study conditions for magnetocentrifugal jet launching from accretion disks around…
The central problem in forming a star is the angular momentum in the circumstellar disk which prevents material from falling into the central stellar core. An attractive solution to the "angular momentum problem" appears to be the…
The origin of jets in young stellar objects (YSOs) remains a subject of active investigation. We present a 3D magnetohydrodynamic simulation of jet launching in YSOs, focusing on the interaction between the stellar magnetosphere and the…
The large-scale magnetic field threading an accretion disk plays an important role in launching jets/outflows. The field may probably be advected inwards by the plasma in the accretion disk from the ambient environment (interstellar medium…
The theory of magnetically accelerated outflows and jets from accretion disks is reviewed at an introductory level, with special attention to problem areas like the launching conditions of the flow at the disk surface, stability of the…
We confirm recent discovery by Cao that in the vicinity of fast rotating black holes jets can be launched centrifugally by cold, magnetized disks even for nearly vertically shaped magnetic flux surfaces. Outflows produced under such extreme…
We examine, parametrically, the interaction between the magnetosphere of a rotating, young stellar object (YSO) and a circumstellar accretion disk using 2.5-D (cylindrically symmetric) numerical magnetoydrodynamic simulations. The…
We present simulations of thin accretion disks around black holes investigating a mean-field disk dynamo in our resistive GRMHD code (Vourellis et al. 2019) that is able to produce a large scale magnetic flux. We consider a weak seed field…
I present and discuss a unified scheme for jet launching that is based on stochastic dissipation of the accretion disk kinetic energy, mainly via shock waves. In this scheme, termed thermally-launched jet model, the kinetic energy of the…
Accretion disks and astrophysical jets are used to model many active astrophysical objects, viz., young stars, relativistic stars, and active galactic nuclei. In this paper we present self-consistent time-dependent simulations of supersonic…
In a comprehensive convergence study, we investigate the computational conditions necessary to resolve disk formation and jet-launching processes, and analyze possible caveats. We explore the magneto-hydrodynamic (MHD) processes of the…
We have performed 3-D numerical magnetohydrodynamic (MHD) jet experiments to study the instabilities associated with strongly toroidal magnetic fields and determine if such magnetic configurations in jets are as unstable as similar…
The powerful narrow jets observed to emanate from many compact accreting objects may arise from the twisting of a magnetic field threading a differentially rotating accretion disk which acts to magnetically extract angular momentum and…