An Incoherent $α-Ω$ Dynamo in Accretion Disks

Details An Incoherent $α-Ω$ Dynamo in Accretion Disks An Incoherent $α-Ω$ Dynamo in Accretion Disks

1995-10-06

arxiv.org/abs/astro-ph/9510038v1

Astronomy and Astrophysics

Astrophysics

23 pages, uses aastex

Scientific paper

We use the mean-field dynamo equations to show that an incoherent alpha effect in mirror-symmetric turbulence in a shearing flow can generate a large scale, coherent magnetic field. We illustrate this effect with simulations of a few simple systems. In accretion disks, this process can lead to axisymmetric magnetic domains whose radial and vertical dimensions will be comparable to the disk height. This process may be responsible for observations of dynamo activity seen in simulations of dynamo-generated turbulence involving, for example, the Balbus-Hawley instability. In this case the magnetic field strength will saturate at $\sim (h/r)^2$ times the ambient pressure in real accretion disks. The resultant dimensionless viscosity will be of the same order. In numerical simulations the azimuthal extent of the simulated annulus should be substituted for $r$. We compare the predictions of this model to numerical simulations previously reported by Brandenburg et al. (1995). In a radiation pressure dominated environment this estimate for viscosity should be reduced by a factor of $(P_{gas}/P_{radiation})^6$ due to magnetic buoyancy.

Affiliated with

Also associated with

No associations

Rating

An Incoherent $α-Ω$ Dynamo in Accretion Disks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with An Incoherent $α-Ω$ Dynamo in Accretion Disks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An Incoherent $α-Ω$ Dynamo in Accretion Disks will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-38904