  Non-thermal hard X-ray and high-energy (HE; 1 MeV < E < 100 GeV) gamma-ray
emission in the direction of Eta Carinae has been recently detected using the
INTEGRAL, AGILE and Fermi satellites. This emission has been interpreted either
in the framework of particle acceleration in the colliding wind region between
the two massive stars or in the very fast moving blast wave which originates in
the historical 1843 "Great Eruption". Archival Chandra data has been reanalysed
to search for signatures of particle acceleration in Eta Carinae's blast wave.
No shell-like structure could be detected in hard X-rays and a limit has been
placed on the non-thermal X-ray emission from the shell. The time dependence of
the target radiation field of the Homunculus is used to develop a single zone
model for the blast wave. Attempting to reconcile the X-ray limit with the HE
-ray emission using this model leads to a very hard electron injection spectrum
dN/dE ~ E^-Gamma with Gamma < 1.8, harder than the canonical value expected
from diffusive shock acceleration.
