| Summary: | 碩士 === 國立中央大學 === 天文研究所 === 105 === LMC X-4 is a high-mass eclipsing X-ray binary consisting of an early type star and a neutron star as an accretor. The orbital period of the binary is 1.4 days. The pulsation period of neutron star is 13.5 $s$. It also has a superorbital modulation of period of 30.5 days caused by the precession of accretion disk periodically obscuring the X-ray emissions from the neutron star.
To study orbital and spin parameter evolutions of LMC X-4, we analyzed archival data collected by Proportional Counter Array on broad Rossi X-ray Timing Explorer in 1996-1999 and XMM-Newton/pn camera in 2003. All archival data were downloaded from the wed site of High Energy Astrophysics Science Archive Reserch Center. Using the orbital Doppler shift of the pulsation, we derived the preliminary orbital and spin parameters. More precision parameters were further refined by pulse arrival time delay technique. Combined with the historical reported values, we adopted O-C method to trace the evolution of $T_{\pi/2}$ and obtained an the orbital period derivative of $\dot{P}_{orb}/P_{orb}=(-9.13\pm0.68)\times10^{-7}$ $yr^{-1}$, and updated the orbital quadratic ephemeris of LMC X-4. We also examined the all reported spin frequencies of LMC X-4 and found that the neutron star experienced spin-down, and up and down epochs with spin frequency derivatives of $(-2.87\pm0.20)\times10^{13}$ $Hz \cdot s^{-1}$, $(6.90\pm0.83)\times10^{13}$ $Hz \cdot s^{-1}$, $(-5.37\pm0.16)\times10^{13}$ $Hz \cdot s^{-1}$ since 1988. About orbital period derivative of LMC X-4, we consider mechanisms of the tidal interaction and the mass-loss causing by stellar wind of companion star. We found that the contribution of mass-loss mechanism is insufficient to account for the measured orbital period derivative. Therefore, the remained mechanism of tidal interaction proposed by \citet{2000ApJ...541..194L} is still considered as the majority mechanism to explain the large orbital period derivative of LMC X-4.
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