Study On The Cyclotron Absorption Line In X-Ray Binaries

X-ray binaries are composed of a compact star(usually neutron star(NS),but also black hole and white dwarf star)and an optical companion,and the compact star emits bright X-ray radiation.The study of NSs in X-ray binaries provides a natural laboratory for us to understand the general relativity process,radiation mechanism,accretion disk,formation and evolution of binaries and other physical processes Magnetic field is an important physical parameter of NSs.The cyclotron absorption line is the only way to directly measure the magnetic field of NSs.We try to study the accretion process and evolution information of X-ray binaries by the physical parameters such as the magnetic field and the spin periods.First of all,we have investigated the progress of cyclotron absorption lines on X-ray energy spectrum in the past 40 years The cyclotron absorption line is used as a probe to detect the magnetic field structure and accretion column geometry of NSs,and the observation and theory are summarized.Then,we compare the magnetic field intensity of the NSs in Hgh mass X-ray binaries(HMXBs)measured by cyclotron absorption line with that of the rotational energy supply pulsar measured by magnetic dipole model.It is found that the magnetic field intensity of NS-HMXBs and young radio pulsars are both normal distribution,and they come from the same distribution.This may indicate that the magnetic field of NSs-HMXBs does not decay in their non accretion acceleration stage(million years),and almost does not decay in their accretion stage(?0.1 million years).Finally,we use the magnetic field intensity information of be/X-ray pulsar based on the cyclotron absorption line to explain the bimodal distribution of its spin period,and think it is caused by the different accretion mass.For the long spin period source,spin period?200 s and magnetic field?5×1012 G,the accretion mass 10-7.5M?;for the short spin periodic source,when the spin is accelerated to?10 s,the magnetic field strength decayed to?5 x 1012 G,and more matter is accreted 10-6.5M?,which will lead to a magnitude of periodic change and a time of magnetic field decay.In the future,with the progress of observation,more and more sources of cyclotron absorption lines will be found.The cyclotron absorption lines make a contribution to the investigations such as the detection of the high magnetic field,the probe of the magnetic field structure of the neutron star and accretion column physics,and so on.