Multiple cyclotron features in the spectra of X-ray binary pulsars:
the extraordinary case of X0115+63.
A. Santangelo et al.
BeppoSAX observations of the February 1999 outburst of the hard
pulsating X-ray transient X0115+63 led to the discovery
of four harmonically spaced cyclotron lines in the spectrum of the source, the
first ever from a cosmic source. These features, that provide a powerful tool
for directly probing the high magnetic field strength which likely characterise
the rotating accreting
neutron stars of many X-ray binary systems, could give us information
on the mechanism and geometry of the accretion processes in the strong
of neutron star. Here, we report results on the spectral behaviour of the source
as a function of the pulse phase, focusing on the phase
dependence of the cyclotron features. Presence of multiple cyclotron features in
of other X-ray pulsars observed by BeppoSAX will be discussed and some of
the aspects yet to be explored will be highlighted.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:18.