Abstract / Description of output
Gradual solar energetic particle (SEP) events, where particles are often
accelerated to 10's of MeV energies, are associated with CME-driven
shocks. As a CME-driven shock propagates, expands and weakens, particles
are accelerated diffusively at the shock. A small number of these
particles travel far enough upstream of the shock and escape into the
interplanetary medium. These escaping energized particles then propagate
along the interplanetary magnetic field (IMF), experiencing only weak
scattering from fluctuations in the IMF. The detection of these
energetic particles prior to the shock arrival often serves as a
precursor for subsequent geomagnetic storms. Although the underlying
acceleration mechanism, diffusive shock acceleration, is reasonably well
understood theoretically, a comprehensive model that tracks particle
acceleration and transport is necessary to interpret observations made
by spacecraft such as ACE and WIND. In this paper, we discuss our
dynamical model of particle acceleration and transport at a propagating
CME-driven shock. The expanding shock is followed numerically using a
shell model. The particle spectrum at the shock is decided by explicitly
calculating the wave intensity due to streaming protons. The transport
of the escaped particles is followed using a Monte-Carlo technique,
which yields the predictions of the temporal intensity profile, particle
spectra, etc. at 1 AU. We have applied this model to the April 21, 2002,
event and find promising agreement between our model simulation and
observations. We believe this approach may provide an important step
towards understanding the influence of large SEP events in
interplanetary and geospace environments.
Original language | English |
---|---|
Title of host publication | Particle Acceleration in Astrophysical Plasmas |
Subtitle of host publication | Geospace and Beyond |
Pages | 51-58 |
Volume | 156 |
Publication status | Published - 2005 |