Related papers: Angular momentum transport through magnetic accret…
(Abridged) We study the dynamical evolution of a stationary, axisymmetric, and perfectly conducting cold accretion disk containing a large-scale magnetic field around a Kerr black hole, trying to understand the relation between accretion…
Magnetic diffusion plays a vital role in star formation. We trace its influence from interstellar cloud scales down to star-disk scales. On both scales, we find that magnetic diffusion can be significantly enhanced by the buildup of strong…
We consider the accretion process in a disk with magnetic fields that are dragged in from the interstellar medium by gravitational collapse. Two diffusive processes are at work in the system: (1) "viscous" torques exerted by turbulent and…
Magnetic fields play an important role in astrophysical accretion discs, and in the interstellar and intergalactic medium. They drive jets, suppress fragmentation in star-forming clouds and can have a significant impact on the accretion…
We report a laboratory study of the transport of angular momentum by a turbulent flow of an electrically conducting fluid confined in a thin disk. When the electromagnetic force applied to the liquid metal is large enough, the corresponding…
This work considers flows from an accretion disk corotating with the aligned dipole magnetic field of a rotating star. Ideal magnetohydrodynamics (MHD) is assumed with the pressure and density related as $p \propto \rho^\gamma$ and with…
We suggest a possible mechanism of efficient transport of the large-scale external magnetic flux inward through a turbulent accretion disk. The outward drift by turbulent diffusion which limits the effectiveness of this process is reduced…
We present the first-ever simulations of non-ideal magnetohydrodynamical (MHD) stellar magnetospheric winds coupled with disc-driven jets where the resistive and viscous accretion disc is self-consistently described. These innovative MHD…
In the early stages of star formation, boundary layer accretion, where protostars accrete material from disks extending down to their surfaces, plays a crucial role. Understanding how a magneto-rotational-instability (MRI)-active disk…
We study the stability of poloidal magnetic fields anchored in a thin accretion disc. The two-dimensional hydrodynamics in the disc plane is followed by a grid-based numerical simulation including the vertically integrated magnetic forces.…
Misalignment between rotation and magnetic field has been suggested to be one type of physical mechanisms which can easen the effects of magnetic braking during collapse of cloud cores leading to formation of protostellar disks. However,…
I show in this paper that two types of magnetic torques can appear in the interaction between an accretion disc and a magnetic accretor. There is the well-known torque resulting from the difference in angular velocity between the accretion…
Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure…
Convection-dominated accretion flow (CDAF) is a promising model to explain underluminous accreting black holes in X-ray binaries and galactic nuclei. I discuss effects of angular momentum transport in viscous hydrodynamical and MHD CDAFs.…
Magnetic diffusion in accretion flows changes the structure and angular momentum of the accreting material. We present two power law similarity solutions for flattened accretion flows in the presence of magnetic diffusion: a…
We discuss results of global 3D MHD simulations of accretion on to a rotating magnetized star with a tilted dipole magnetic field, where the accretion is driven by the magneto-rotational instability (MRI). The simulations show that…
We present the first-ever simulations of non-ideal magnetohydrodynamical (MHD) stellar winds coupled with disc-driven jets where the resistive and viscous accretion disc is self-consistently described. The transmagnetosonic, collimated MHD…
Large scale magnetic field threading an accretion disk is a key ingredient in the jet formation model. The most attractive scenario for the origin of such a large scale field is the advection of the field by the gas in the accretion disk…
According to the standard thin disc theory, it is predicted that the radiation-pressure-dominated inner region of a thin disc is thermally unstable, while observations suggest that it is common for a thin disc of more than 0.01 Eddington…
The concentration of magnetic flux near the poles of rapidly rotating cool stars has been recently proposed as an alternative mechanism to dynamo saturation in order to explain the saturation of angular momentum loss. In this work we study…