相关论文: Accretion Disks and Dynamos: Toward a Unified Mean…

The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century.…

We review the current theoretical models of the inward advection of the large scale external magnetic fields in accretion discs. The most plausible theories for launching astrophysical jets rely on strong magnetic fields at the inner parts…

We report new global ideal MHD simulations for thin accretion disks (with thermal scale height H/R=0.1 and 0.05) threaded by net vertical magnetic fields. Our computations span three orders of magnitude in radius, extend all the way to the…

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…

Some recent results and open issues in magnetic dynamo theory are addressed. The distinction between small-scale and mean-field dynamo (MFD) action in forced turbulent flows is emphasized. Though useful, the MFD has been controversial. This…

The evolution of the magnetic field from the large-scale dynamo is considered a central feature of the accretion disk around a black hole. The resulting low-frequency oscillations introduced from the growth and decay of the field strength,…

We briefly review recent developments in black hole accretion disk theory, placing new emphasis on the vital role played by magnetohydrodynamic (MHD) stresses in transporting angular momentum. The apparent universality of accretion-related…

Accretion disks are observed in young stars, cataclysmic variables, binary X-ray sources et al. Accretion disk theory was first developed as a theory with the local heat balance, where the whole energy produced by a viscous heating was…

Activity of the nuclei of galaxies and stellar mass systems involving disk accretion to black holes is thought to be due to (1) a small-scale turbulent magnetic field in the disk (due to the magneto-rotational instability or MRI) which…

We present a 3-D ideal MHD simulation of magnetospheric accretion onto a non-rotating star. The accretion process unfolds with intricate 3-D structures driven by various mechanisms. First, the disc develops filaments at the magnetospheric…

We have carried out and analyzed a set of axisymmetric MHD simulations of the evolution of a turbulent/diffusive accretion disc around an initially unmagnetized star. The disc is initially threaded by a weak magnetic field where the…

Large-scale magnetic fields are relevant for a number of dynamical processes in accretion disks, including driving turbulence, reconnection events, and launching outflows. Numerical simulations have indicated that the initial strengths and…

Cold steady-state disk wind theory from near Keplerian accretion disks requires a large scale magnetic field at near equipartition strength. However the minimum magnetization has never been tested. We investigate the time evolution of an…

Accretion disc theory was first developed as a theory with the local heat balance, where the whole energy produced by a viscous heating was emitted to the sides of the disc. One of the most important new invention of this theory was a…

We review the current status of studies on accretion and protoplanetary disks of young stars with large-scale magnetic fields. Observational data on magnetic fields of the disks are compiled and analysed. Modern analytical and numerical MHD…

Accretion disk theory was first developed as a theory with the local heat balance, where the whole energy produced by a viscous heating was emitted to the sides of the disk. One of the most important new invention of this theory was the…

We present MHD simulations exploring the launching, acceleration and collimation of jets and disk winds. The evolution of the disk structure is consistently taken into account. Extending our earlier studies, we now consider the…

Magnetic fields are important for accretion disc structure. Magnetic fields in a disc system may be transported with the accreted matter. They can be associated with either the central body and/or jet, and be fossil or dynamo excited in…

Recent advances in mean-field theory are reviewed and applications to the Sun, late-type stars, accretion disks, galaxies, and the early Universe are discussed. We focus particularly on aspects of spatio-temporal nonlocality, which is one…

(Abridged) We report results of three dimensional MHD simulations of global accretion disks threaded with weak vertical magnetic fields. We perform the simulations in the spherical coordinates with different temperature profiles and…