The pulse shape and spectrum of the millisecond pulsar PSR J0218+4232 in the energy band 1-10 keV observed with BeppoSAX

We present the results of a BeppoSAX observation of PSR J0218+4232 which, for the first time, provides detailed information on the pulsar's temporal and spectral emission properties in the broad band 1-10 keV. We detected X-ray pulses with a pulsed fraction of 73+/-12%. The pulse profile is characterized by two peaks phase separated by Delta phi =0.47+/-0.05. The pulsed spectrum is best described by a power-law of photon index 0.61+/-0.32 with an unabsorbed (2-10 keV) X-ray flux of 4.1x10^-13 erg cm^-2 s^-1 implying a luminosity of L_x = 1.3x 10³² Theta ; (d/5.7;kpc)² erg s^-1 and an X-ray efficiency of L_x/dot {E}=4.8x 10^-4 Theta ; (d/5.7;kpc)² where Theta is the solid angle spanned by the emission beam.