BeppoSAX observations of the X-ray binary pulsar 4U1626-67

We report on observations of the low-mass X-ray binary 4U1626-67 performed during the BeppoSAX Science Verification Phase. We present the broad-band 0.1-100 keV pulse averated spectrum, that is well fit by a two-component function: a 0.27 ± 0.02 keV blackbody and an absorbed power law with a photon index of 0.89 ± 0.02. A very deep and narrow absorption feature at 38 keV, attributable to electron cyclotron resonance, is clearly visible in the broad-band spectrum. It corresponds to a neutron star magnetic field strength of 3.3 x 1012 G. The 4U1626-67 pulse profiles show a dramatic dependence on energy: the transition between the low energy (E < 10 keV) bi-horned shape to the high-energy (E > 10 keV) sinusoidal profile is clearly visible in our data. The modulation index shows a monotonic increase with energy