X-Ray emission from SN 2004dj: A Tale of Two Shocks
  Type IIP (Plateau) Supernovae are the most commonly observed variety of core
collapse events. They have been detected in a wide range of wavelengths from
radio, through optical to X-rays. The standard picture of a type IIP supernova
has the blastwave interacting with the progenitor's circumstellar matter to
produce a hot region bounded by a forward and a reverse shock. This region is
thought to be responsible for most of the X-ray and radio emission from these
objects. Yet the origin of X-rays from these supernovae is not well understood
quantitatively. The relative contributions of particle acceleration and
magnetic field amplification in generating the X-ray and radio emission need to
be determined. In this work we analyze archival Chandra observations of SN
2004dj, the nearest supernova since SN 1987A, along with published radio and
optical information. We determine the pre-explosion mass loss rate, blastwave
velocity, electron acceleration and magnetic field amplification efficiencies.
We find that a greater fraction of the thermal energy goes into accelerating
electrons than into amplifying magnetic fields. We conclude that the X-ray
emission arises out of a combination of inverse Compton scattering by
non-thermal electrons accelerated in the forward shock and thermal emission
from supernova ejecta heated by the reverse shock.
