Flow and distribution of magnetic energy in accretion disks: a kinematic approach.

Details Flow and distribution of magnetic energy in accretion disks: a kinematic approach. Flow and distribution of magnetic energy in accretion disks: a kinematic approach.

Nov 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996a%26a...315..638s&link_type=abstract

Astronomy and Astrophysics, v.315, p.638-653

Astronomy and Astrophysics

Astrophysics

1

Accretion Disks, Mhd, Plasmas, Turbulence, Stars: Individual: Lmc X-3

Scientific paper

By taking account of the statistical nature of kinematic mean field dynamo theory, it is pointed out that the mean magnetic field should always vanish. A more fruitful approach therefore seems to be to study the dynamics of the second moment of magnetic field which contains information on mean magnetic energy and statistical correlations between the various components of the magnetic field. The general dynamics of this tensor are discussed. As an application a stationary solution for zero helicity is presented in a local approximation. It is found that such a dynamo can only be maintained by compressible turbulence. The implications of this non-helical solution for the structure and emission of stationary thin accretion disks are discussed. The limits of applicability of the kinematic approach are briefly discussed. We apply our model to the inner region of the accretion disk around the black hole candidate LMC X-3. We find typical rms magnetic field strength values in the range 4x10^6^-4x10^7^Gauss.