We report the hard X-ray properties of the young Crab-like LMC pulsar \object PSR B0540-69 , using archival RXTE PCA ( 2 – 60 keV ) and RXTE HEXTE ( 15 – 250 keV ) data .
Making use of the very long effective exposure of 684 ks , we derived a very detailed master pulse profile for energies 2 – 20 keV .
We confirm the broad single-pulse shape with a dip in the middle and with a significant fine structure to the left of the dip .
For the first time pulse profiles in the 10 – 50 keV energy interval are shown .
Remarkably , the coarse pulse shape is stable from the optical up to X-ray energies analogous to the case of the Crab pulsar ( \object PSR B0531+21 ) .
The profiles can be described with two Gaussians with a phase separation of \sim 0.2 ; the distribution of the ratios between the two components from the optical to the X-ray range is consistent with being flat .
Therefore we can not conclude that the profile consists of two distinct components .
We also derived a new total pulsed spectrum in the \sim 0.01 – 50 keV range in a consistent analysis including also archival ROSAT PSPC ( 0.01 – 2.5 keV ) data .
This spectrum can not be described by a single power-law , but requires an additional energy dependent term .
The bending of the spectrum around 10 keV resembles that of the Crab pulsar spectrum .
Although model calculations using Outer Gap scenarios could probably explain the high-energy characteristics of PSR B0540-69 as they successfully do for the Crab , our measurements do not entirely agree with the latest calculations by .
The small discrepancies are likely to be caused by uncertainties in the pulsar ’ s geometry .