Forgot your password?
A Clash of Clusters Provides New Clue to Dark Matter
Special ACKS Seminar: Dragan Huterer
Document Actions
ACKS Seminar: Dmitri Uzdensky (Princeton University)
| What | ACKS |
|---|---|
| When |
21 February 08 from 04:00 pm to 04:00 pm |
| Where | CAMPUS: Phys & Astrophys Bldg., 1st fl., conf rm (102/103) |
| Contact Name | Lukasz Stawarz |
| Contact Email | stawarz@slac.stanford.edu |
| Add event to calendar |
vCal (Windows, Linux)
iCal (Mac OS X)
|
Magnetized Coronae of Stars and Accretion Disks
I present a general physical picture of magnetically-active astrophysical coronae, e.g., of stars and accretion disks. I first describe a statistical theory of the magnetic field in the corona above a turbulent accretion disk. The field is represented by an ensemble of loops that evolve under Keplerian shear, random disk footpoint motions, and reconnection with other loops. I construct and solve numerically a kinetic equation for the loop distribution function and use the steady state solution to calculate the total magnetic energy in the corona, its distribution with height, the overall coronal torque, etc. I show that these quantities grow strongly with increased rate of Keplerian shear relative to magnetic reconnection, underscoring the importance of reconnection in accretion disk coronae. In the second part of my talk I argue that recent advances in magnetic reconnection enable significant progress in understanding magnetized coronae as self-regulating, marginally collisionless systems. The self-regulating coronal heating mechanism is based on an interplay of two effects: (1) the transition between slow collisional and fast collisionless reconnection regimes and (2) plasma evaporation from the star's or disk's surface in response to coronal energy release. I show how these ideas work in the solar corona and in the inner parts of black hole accretion disk coronae.
Stanford High Performance Computing Conference IV