Abstract
PSR B1951+32, like other EGRET-detected high-energy pulsars, shows a power-law spectrumin theEGRET energy band. However, characteristics of this pulsar in soft and hard X-ray bandsstill remain uncertain. In thispaper wereport resultsof atiminganalysisof PSR B1951+32 based on ASCA data taken in 1993 and RXTE data taken in 1996 ranging from 0.5keV to250keV. Weapplycontemporaneousradioephemeridesandvariousstatistical tests to search for evidence of pulsation. Although these analyses all fail to find pulsation in the time series, useful upper limits are derived. The estimated upper limits are consistent with the trend of spectral turn-over fromhigh-energy gamma-ray emissions towards lower-energy bands. We give detailed discussions which argue that such turn-over strongly suggests the outer magnetosphereas theemission site for pulsed gamma-rays. On theother hand, they are not consistent with thereportedpower-law spectrafromthepoint sourceobservedby ROSAT in the 0.1-2.4 keV band with an assumed constant pulsed fraction. The pulsed soft X-ray emission detected by ROSAT must follow a much softer spectrum than that of the overall point source. This in turn suggestsarelatively strongunpulsed power-law component beyond about 1 keV, whoseactual spectral behavior calls for futureobservations. PACS. 97.60.Gb – Pulsars. I.