Astrophysical shocks can accelerate charged particles through diffusive
shock acceleration. This process involves repeated shock crossings where
the particle gains energy from collisions with the electromagnetic
field. Eventually, these particles will reach relativistic speeds and
can be observed as cosmic rays.
In order to simulate this process, we need a method that can handle
both the large-scale structure of astrophysical shocks, as well as the
behaviour of individual particles. We achieve this by combining the
classical magnetohydrodynamics (MHD) and particle-in-cell (PIC) methods.
This allows us to describe the thermal plasma of the shock through MHD,
while simultaneously using PIC to follow the movement of non-thermal
particles as they are accelerated. Our results show a complicated
interaction that destabilizes the shock, reducing the efficiency with
which particles can be accelerated. |