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Event Number 3282

  Thursday, February 13th, 2014

Astronomy Colloquium
Asymmetries in Protoplanetary Transition Disks
Time: 3:30 pm
Place: 4421 Sterling Hall
Speaker: Hui Li, Los Alamos National Laboratory
Abstract: Particle energization in astrophysical systems is a challenging yet fascinating subject. Observations from radio to gamma-rays of AGN jets, supernova remnants, pulsars, gamma-ray bursts, etc., have provided important clues. In this talk, we explore the energy conversion processes in a parameter regime when the magnetic energy density overwhelms the particle energy density (including its rest mass energy density). Such a condition has been discussed in the context of AGN jets and pulsars. We present two-dimensional and three-dimensional relativistic, full kinetic simulations that show fast magnetic reconnection can occur in highly magnetized plasmas, with the magnetization parameter ranging from unity to 1600. The fast magnetic dissipation leads to a fast, nonthermal particle acceleration, yielding a power law distribution with a hard spectrum. Detailed analyses show that the acceleration in the power-law range is mainly by a Fermi-like mechanism in the relativistic flows generated by reconnection. Implications for observations will be discussed.
Host: Professor and Dept Chair Ellen Zweibel
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