A RADIO X-RAY COMPARISON OF THE VELA-X REGION

We present a VLA image of the Vela X region, a nebula thought to be po wered by the young pulsar B0833-45, at a resolution of approximately 1 .'3. The morphology of this synchrotron nebula is dominated by a netwo rk of fine, overlapping linear filaments. The brightest filament lies just south of PSR B0833-45 and can be traced to the center of Vela X, 40' away. This radio filament appears to be the counterpart of an X-ra y feature first detected by Markwardt & Ogelman (1995). Rather than a one-to-one position alignment between them, the radio filament is syst ematically offset and traces the eastern boundary of the X-ray feature . We consider several models for the origin of the radio filament and its relation to the X-ray feature. At present, the data cannot disting uish between whether the radio emission is due to electrons accelerate d in situ or whether the radio emission results from the compression o f the relativistic pulsar wind. We suggest several possible observatio ns to enable us to distinguish which hypothesis is correct.