A Rossi X-Ray Timing Explorer observation of the vela pulsar: Filling in the X-ray gap

We have detected pulsed emission from the Vela pulsar at 2-30 keV during a 93 ks observation with the Rossi X-Ray Timing Explorer (RXTE). The RXTE pul se profile shows two peaks, which are roughly in phase with the EGRET peaks , but does not show any significant interpeak emission. The phase of peak 2 is energy dependent, moving to higher phase with increasing energy in the RXTE band, in phase alignment with the second optical pulse in the lowest e nergy band (2-8 keV) and in phase alignment with the second EGRET pulse in the highest energy band (16-30 keV). The average pulse spectrum joins smoot hly to the high-energy spectrum of OSSE, COMPTEL, and EGRET, although the s pectrum of peak 1 is significantly harder than that of peak 2. A break or t urnover in the spectrum around 50 keV, previously suggested by OSSE data, i s now clearly defined. The RXTE spectrum falls several orders of magnitude below the ROSAT emission in the 0.1-2 keV band, suggesting a thermal origin for the ROSAT pulse.