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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20091105T000000
DTEND;TZID=Atlantic/Canary:20091105T010000
UID:iactalks-79
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/79
CREATED:2009-11-05T00:00:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Relativistic hydro and magnetohydrodynamic models for AGN jet propa
 gation and deceleration
DESCRIPTION:Relativistic hydro and magnetohydrodynamic models for AGN jet p
 ropagation and deceleration\nProf. Rony Keppens\n\nI will present grid-ada
 ptive computational studies of both magnetized and unmagnetized jet flows,
  with significantly relativistic bulk speeds, as appropriate for AGN jets.
  Our relativistic jet studies shed light on the observationally establishe
 d classification of Fanaroff-Riley galaxies, where the appearance in radio
  maps distinguishes two types of jet morphologies. We investigate how dens
 ity changes in the external medium can induce one-sided jet decelerations,
  explaining the existence of hybrid morphology radio sources. Our simulati
 ons explore under which conditions highly energetic FR II jets may suddenl
 y decelerate and continue with FR I characteristics.\nIn a related investi
 gation, we explore the role of dynamically important, organized magnetic f
 ields in the collimation of the relativistic jet flows. In that study, we 
 concentrate on morphological features of the bow shock and the jet beam, f
 or various jet Lorentz factors and magnetic field helicities. We show that
  the helicity of the magnetic field is effectively transported down the be
 am, with compression zones in between diagonal internal cross-shocks showi
 ng stronger toroidal field regions. For the high speed jets considered, si
 gnificant jet deceleration only occurs beyond distances exceeding hundred 
 jet radii, as the axial flow can reaccelerate downstream to internal cross
 -shocks. This reacceleration is magnetically aided, due to field compressi
 on across the internal shocks which pinch the flow.
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