Suzaku Detection of Diffuse Hard X-Ray Emission outside Vela X
  Vela X is a large, 3x2 degrees, radio-emitting pulsar wind nebula (PWN) powered by the Vela pulsar in the Vela supernova remnant. Using four Suzaku/XIS observations pointed just outside Vela X, we find hard X-ray emission extending throughout the fields of view. The hard X-ray spectra are well represented by a power-law. The photon index is measured to be constant at Gamma~2.4, similar to that of the southern outer part of Vela X. The power-law flux decreases with increasing distance from the pulsar. These properties lead us to propose that the hard X-ray emission is associated with the Vela PWN. The larger X-ray extension found in this work strongly suggests that distinct populations relativistic electrons form the X-ray PWN and Vela X, as was recently inferred from multiwavelength spectral modeling of Vela X. 
Satoru Katsuda (1), Koji Mori (2), Robert Petre (1), Hiroya Yamaguchi   (3), Hiroshi Tsunemi (4), Fabrizio Bocchino (5), Aya...
astro-ph.HE