  Morphologically it appears as if the Vela X PWN consists of two emission
regions: whereas X-ray (1 keV) and very high energy (VHE) H.E.S.S. gamma-ray
observations appear to define a cocoon type shape south of the pulsar, radio
observations reveal an extended area of size 2 deg by 3 deg (including the
cocoon area), also south of the Vela pulsar. Since no wide field of view (FoV)
observations of the synchrotron emission between radio and X-rays are
available, we do not know how the lepton (e+/-) spectra of these two components
connect and how the morphology changes with energy. Currently we find that two
distinct lepton spectra describe the respective radio and X-ray/VHE gamma-ray
spectra, with a field strength of 5 muG self-consistently describing a
radiation spectral break (or energy maximum) in the multi-TeV domain as
observed by H.E.S.S. (if interpreted as IC radiation), while predicting the
total hard X-ray flux above 20 keV (measured by the wide FoV INTEGRAL
instrument) within a factor of two. If this same field strength is also
representative of the radio structure (including filaments), the implied IC
component corresponding to the highest radio frequencies should reveal a
relatively bright high energy gamma-ray structure and Fermi LAT should be able
to resolve it. A higher field strength in the filaments would however imply
fewer leptons in Vela X and hence a fainter Fermi LAT signal.
