A Rossi X‐Ray Timing Explorer Observation of the Vela Pulsar: Filling in the X‐Ray Gap

Abstract

We have detected pulsed emission from the Vela pulsar at 2-30 keV duringa 93 ks observation with the Rossi X-Ray Timing Explorer (RXTE).The RXTE pulse profile shows two peaks, which are roughly in phasewith the EGRET peaks, but does not show any significant interpeakemission. The phase of peak 2 is energy dependent, moving to higherphase with increasing energy in the RXTE band, in phase alignmentwith the second optical pulse in the lowest energy band (2-8 keV)and in phase alignment with the second EGRET pulse in the highestenergy band (16-30 keV). The average pulse spectrum joins smoothlyto the high-energy spectrum of OSSE, COMPTEL, and EGRET, althoughthe spectrum of peak 1 is significantly harder than that of peak2. A break or turnover in the spectrum around 50 keV, previouslysuggested by OSSE data, is now clearly defined. The RXTE spectrumfalls several orders of magnitude below the ROSAT emission in the0.1-2 keV band, suggesting a thermal origin for the ROSAT pulse.