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SUMMARY:Evidence for a Cosmic Battery - Denise Gabuzda (University College
  Cork)
DTSTART:20120124T163000Z
DTEND:20120124T173000Z
UID:TALK35850@talks.cam.ac.uk
CONTACT:26880
DESCRIPTION:In a standard theoretical picture of the formation and launchi
 ng of astrophysical jets\, the jets should acquire helical magnetic fields
 \, due essentially to the combination of the rotation of the central black
  hole and accretion disk and the jet outflow.  One way such helical fields
  may be manifest is through their tendency to give rise to gradients in th
 e observed local Faraday rotation across the jet\, due to the systematic v
 ariation of the line-of-sight component of the helical magnetic field acro
 ss the jet.  Indeed\, transverse Faraday rotation gradients have been obse
 rved across a number of AGN jets on both parsec and kiloparsec scales\, pr
 oviding direct evidence that they carry toroidal or helical magnetic field
 s.  The directions of the observed transverse Faraday rotation gradients p
 rovide statistical evidence for the operation of a cosmic “battery” in
  the accretion disks of AGN\, which couples the direction of rotation and 
 the direction of the poloidal (axial) field of the jet.  If this “batter
 y” is indeed operating\, we have detected the presence of ordered curren
 ts and magnetic fields on a grand scale.\n
LOCATION:Ryle Seminar Room\, Cavendish Laboratory
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