| X-ray binaries consist of a compact object and a normal star,and the accretion onto the compact star produces X-ray emission.In my work,I mainly focus on neu-tron star and black hole systems.The study of the formation and evolution of X-ray binaries requires the combination of many different fields.Therefore,I firstly give an overview of the background knowledge of my research in the first chapter.Firstly,I in-troduce accretion process taking place around the compact object and accretion-induced spin evolution of neutron star;then,I discuss the mechanisms driving and effecting bi-nary evolution:orbital angular momentum loss mechanism and mass transfer;next,I describe the observed properties of neutron star/black hole X-ray binaries and related possible explanation;finally,I summarize the standard picture of the formation and evolution of neutron star/black hole X-ray binaries and unsolved issues.Then,the fol-lowing three chapters introduce my published works during my master degree study.The second chapter settles the very fast orbital shrinkage phenomenon observed in several black hole low-mass X-ray binaries(BHLMXBs),which is difficult to under-stand in the standard picture of the LMXB evolution.Based on the possible detection of a circumbinary(CB)disk in A0620-00 and XTE J1118+480,we investigate the in-fluence of a CB disk on the evolution of inner binary by using the MESA code.We consider two cases for the CB disk formation in which it is fed by mass loss during single outburst or successive outbursts in the LMXB.We show that when taking rea-sonable values of the initial mass and the dissipating time of the disk,it is possible to explain the fast orbital shrinkage in the BHLMXBs without invoking a high mass transfer rate.The third chapter study the possibility that a BHLMXB harbors pre-main-sequence(pre-MS)donor star.We investigate the evolution of low-mass pre-MS stars in binaries with a BH companion with the MESA code.We find that,because of the relatively slow rotation of the pre-MS star after the common envelope evolution and the long turnover time in the pre-MS stars,tidal torque is not always able to synchronize the pre-MS star,so the spin periods are generally longer than the orbital periods.Mass transfer can occur only for stars with mass larger than ~1.2 M,which experience expansion due to nuclear reaction after the Hayashi contraction phase.The effective temperatures and orbital periods of these systems do not match the observations of BHLMXBs with lithium overabundances,which means that they are unlikely to host pre-MS donor stars.The fourth chapter investigate the bimodal distribution of pulse period of Be/X-ray pulsars,peaking at ~10 s and-200 s,respectively.We investigate the spin evolution of Be/X-ray pulsars based on the magnetically threaded accretion disk model.Com?pared with previous works,we take into account several distinct and important factors of Be/X-ray binaries,including the transient accretion beha’vior and possible change of the accretion disk structure during quiescence.We demonstrate that current Be/X-ray pulsars are close to the spin equilibrium determined by the balance of spin-up during outbursts and spin down during quiescence,and that the observed bimodal distribution can be well reproduced by the equilibrium spin periods with reasonable input parame-ters.The last chapter summarizes my works in the above chapters,discuss my future works,and present preliminary results.Because of the asymmetry generated in super-nova,compact objects usually have fast initial velocities after the explosion,which is named natal kick.Although kick velocity play important roles in the formation of X-ray binaries and double compact object binaries,kick velocity is poorly constrained both observationally and theoretically.In my future work,I plan to constrain kick velocity and types of supernovae though binary population synthesis method. |
