The extended hard X-ray emission from the Vela Plerion

We present the results of a broad band (3-200 keV) spectral analysis of BeppoSAX and XMM-Newton observations of the Vela plerion. The hard X-ray (>15 keV) emission is found to be extended over a region of 12'-15' radius, corresponding to a size of about 1.0-1.3 pc for a source distance of 290 pc. A single power law does not give an acceptable fit while a broken power law or a log-parabolic law nicely fit the data. The former spectral model has the photon index Γ₁ = 1.66±0.01 for energies lower than the break value equal to 12.5 keV and the index Γ₂ = 2.01±0.05 up to about 200 keV. The total X-ray luminosity of the Vela plerion is L_X=5.5×10³³ erg s^-1, which implies a conversion factor of the spin-down power of ~10^-3.