X-ray Timing Observations of PSR J1930+1852 in the Crab-like

We present new X-ray timing and spectral observations of PSR J1930+1852, the young energetic pulsar at the center of the non-thermal supernova remnant G54.1+0.3. Using data obtained with the Rossi X-ray Timing Explorer (RXTE) and Chandra X-ray observatories we have derived an updated timing ephemeris of the 136 ms pulsar spanning 6 years. During this interval, however, the period evolution shows significant variability from the best fit constant spin-down rate of u P = 7.5112(6)×10 −13 s s −1 , suggesting strong timing noise and/or glitch activity. The X-ray emission is highly pulsed (71 ± 5% modulation) and is characterized by an asymmetric, broad profile (∼ 70% duty cycle) which is nearly twice the radio width. The spectrum of the pulsed emission is well fitted with an absorbed power law of photon index = 1 .2 ± 0.2; this is marginally harder than that of the unpulsed component. The total 2 − 10 keV flux of the pulsar is 1.7 × 10 −12 erg cm −2 s −1 . These results confirm PSR J1930+1852 as a typical Crablike pulsar.