Speaker
Prof.
Masahiro Hoshino
(The University of Tokyo)
Description
Nonthermal particles are ubiquitous in space and astrophysical
plasmas, and
explosive phenomena such as supernova remnant shocks, solar flares,
and
terrestrial substroms have demonstrated evidence for the production of
high-energy
particles. Yet the particle acceleration mechanism remains an
unresolved issue.
After the innovative idea of the stochastic acceleration by Enrico Fermi
in 1949,
many researchers have investigated the diffusive shock acceleration
model to
explain nonthermal particle, but the diffusive shock acceleration alone
cannot
explain the observed efficient nonthermal particles. Instead of the
shock
acceleration, magnetic reconnection is now thought to be another
important agent.
We argue that the combination of the original Fermi acceleration model
and the
magnetic reconnection process is one of the possible paths to
accelerate the thermal
plasmas to the high energy nonthermal particles. We also discuss that
the turbulent
magnetic reconnection with many magnetic islands/plasmoids can
naturally happen
in many space and astrophysical settings.
Author
Prof.
Masahiro Hoshino
(The University of Tokyo)
