MG12 - Talk detail
 

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Abstract

MHD of a large scale magnetic field in the advective accretion disks.

The problem of the formation of a large-scale magnetic field in the accretion disks around black holes is reconsidered, with account the nonuniform vertical structure of the disk. The high electrical conductivity of the outer layers of the disk prevents the outward diffusion of the magnetic field. This implies a stationary state with a strong magnetic field in the inner parts of the accretion disk close to the black hole. Global solution of advective accretion disk structure around a black hole is constructed numerically. At high luminosity there is a continuous transition between the optically thick outer and optically thin inner disk regions. Models of accretion flows with large mass accretion rates are considered using a bridging formula for radiative losses at high and low effective optical depths. Contrary to the models neglecting advection, the global solutions have been found for all investigated range of accretion rates. The presence of the effectively optically thin regions in the innermost part of accretion disks results in a significant increase of the plasma temperature in those regions and this increase can be discriminated in observations in the form of the observed hard radiation tails.

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