Hard X-ray timing and spectral characteristics of the energetic pulsar PSR J0205+6449 in supernova remnant 3C 58: An RXTE PCA/HEXTE and XMM-Newton view on the 0.5-250 keV band

Context. PSR J0205+6449 is a young rotation-powered pulsar in SNR 3C 58. It is one of only three young (<10 000 year old) pulsars that have so far been detected in the radio and the classical X-ray bands, as well as at hard X-rays above 20 keV and at high-energy (>100 MeV) gamma-rays. The other two young pulsars are the Crab and PSR B1509-58.
Aims. Our aim is to derive the timing and spectral characteristics of PSR J0205+6449 over the broad X-ray band from similar to 0.5 to similar to 270 keV.
Methods. We used all publicly available RXTE observations of PSR J0205+6449 to first generate accurate ephemerides over the period September 30, 2000-March 18, 2006. We then employed phase-folding procedures yielded pulse profiles using data from RXTE PCA and HEXTE, and XMM-Newton EPIC PN. All profiles were phase aligned with a radio profile derived from the Jodrell Bank Observatory data, and the time-averaged timing and spectral characteristics of the pulsed X-ray emission were derived.
Results. Our timing solutions are consistent with earlier results, but we detect sharper structures in the PCA X-ray profile. The X-ray pulse profile consists of two sharp pulses, separated in phase by 0.488 +/- 0.002, that can be described by 2 asymmetric Lorentzians, each with the rising wing steeper than the trailing wing, and full-width-half-maximum 1.41 +/- 0.05 ms and 2.35 +/- 0.22 ms, respectively. For the second, weaker pulse we find an indication of a flux increase by a factor similar to 2, about 3.5 sigma above the time-averaged value, over a two-week interval, during which its pulse shape did not change. The spectrum of the pulsed X-ray emission is non-thermal in origin, exhibiting a power-law shape with photon index Gamma = 1.03 +/- 0.02 over the energy band similar to 0.5 to similar to 270 keV. In the energy band covered with the PCA (similar to 3-30 keV), the spectra of the two pulses have the same photon index, namely, 1.04 +/- 0.03 and 1.10 +/- 0.08, respectively. Comparisons of the detailed timing and spectral characteristics of PSR J0205+6449 in the radio, hard X-ray, and gamma-ray bands with those of the Crab pulsar, PSR B1509-58 and the middle-aged Vela pulsar uncover more differences than similarities.